[Dprglist] The KR01 Robot Project

Murray Altheim murray18 at altheim.com
Mon Dec 23 02:48:38 PST 2019

Carl Ott via DPRGlist wrote:
 > Hi Murray,
 > Welcome to the DPRG mailing list - Thanks for reaching out - Hello New
 > Zealand!

Hi Carl,

Sorry to take so long to get back to you -- I've been a bit busy. For those
who don't want to read this entire message, the "Executive Summary" is that
while in the process of responding to your message I've somehow started the
New Zealand Personal Robotics Group. More on that (including links) below...

And apologies that this message is so long - we'd covered a lot of different

 > No kidding about doing an 8085 based computer in 1979 as a high school
 > student - that puts you pretty close the great Woz of Cupertino :)

The 80C85 was notably the same CPU used in the NASA Mars Sojourner robot.
I certainly didn't take it as far as they did... but my budget was smaller.

I didn't think about it so much at the time, but I now feel enormously
fortunate to have been schooled in Canada and Iowa and California, at the
time some of best places in North America to get an education.

The fact that in junior and senior high I was building CMOS and TTL circuits,
learning how to use a milling machine, reading Latin, roasting a quail (in
home economics class) I don't put down to my own talent so much as finding
myself in a great learning environment, with enthusiastic and supportive
teachers, they are my real heroes.

We need to make sure today's kids have at least as good an environment:
their challenges are likely to be a lot greater than ours.

 > You mentioned servo mounting a LiDAR - some DPRG members have done that.
 > Some have also dabbled with the constant rotation LiDAR - speak up if you'd
 > like chat about those - they'll give you lots more data than you could get
 > with a servo mounted LiDAR.

When I mapped out the requirements for my project I decided I wanted the
robot to be roughly on the scale of David Anderson's SR04: not tiny, but
not very large.

I'd seen the US$115 LIDAR on the Adafruit site but I think its cost, size,
and usage would kinda overwhelm my project. If there are any tiny LIDARs
suitable to the scale of my robot I'd be keen to learn about them, but I'm
mostly focused on the ToF sensor along with the sonar together as the
robot's long range "vision"; both are mounted on the servo.

Power Supplies .............................................................

 > I've recently purchased some Pimoroni OnOff Power Shims to get my Pi
 > projects off to a robust start, and hopefully avoid corrupting the file
 > system with unceremonious power yanks. Have you tried those? I'm about
 > ready to install the first one and check it out...

No, I'm using a PiJuice unit, effectively a UPS for a Pi, which comes
standard with a 1820mA LiPo battery. The power/battery management features
seem very promising. PiJuice also sell 1200mA, 2000mA, 5000mA and 12000mA
compatible batteries.

I didn't want to stress the LiPo with the motors, so I'm using a Thunderborg
and a Makita 12V power tool battery. The 18V Makita batteries proved too
large for the OSEPP kit, even modified as I've done. Since I'm not planning
on going off-road (this is strictly a house robot) I may end up putting the
18V battery on the top of the robot or hanging it off the back if the 12v
proves to have too little capacity/running time.

OSEPP Kits ...............................................................

 > I've also noticed the OSEPP kits - so it will be nice to hear about your
 > experience with those.  Would it take much encouragement to have you
 > blog about your project as it comes along?

I'm pretty impressed all around with the OSEPP tank kit. The parts are
made of red-anodized aluminum and are quite beautiful. The red machined
wheels are extremely light and can either support tank treads made out of
silicon rubber links held together with stainless pins, or silicon tires.
I've purchased a set of 4 tires in case I'm not happy with the tank
treads (see below).

My only criticism is that OSEPP isn't Lego: they provide a number of
accessory kits but not much in the way of individual parts. Their "Double
Beams" come in 6, 8 and 9 hole kits, and I bought an extra size 9 kit,
which comes with some small plates and some very valuable "beam connectors".
But the three red plates are all different (i.e., you can't use them in a
left-right symmetrical arrangement) and you can't buy beam connectors on
their own, so if you run out you have to buy another large kit.

Online there's been some criticism of the durability of the tank treads. A
few days ago I was (gently) taking the treads off of the robot and had a
tread piece tear. As that was my last spare I contacted OSEPP and they very
quickly sent me an entire kit of replacement tread parts (even going so far
as to sending the order to me from Mouser) but according to their reply aren't
planning to create any new products or packaging of their existing products.
I'm not sure if I should read anything into that, but their product support
so far seems very good.

Alternative Processors ....................................................

One thing I thought to mention is that while I'm using a Raspberry Pi for
my controller, I've investigated several alteratives. Due to a bug in the Pi
related to clock stretching it can't support the 9-DoF sensor directly, so
I'm using an ItsyBitsy M4 Express as an I2C slave processor for the BNO05
9-DoF sensor and the bumper and encoder processors (which would be bespoke
TTL, though I may end up using software debouncing). The M4 also has lots of
analog and digital GPIO pins so it's a good place to offload sensor
processing from the Pi. It's also a nice way to learn about master-slave I2C
processors. This means I'll have a sub-project of the M4 and the BNO05 sensor
on a daughterboard.

The M4 Express directly supports CircuitPython and therefore might be a
suitable processor for your project. It runs at 120MHz so it's no slouch.
I wanted WiFi since one of my own requirements is the ability to SSL into my
robot. If that's the case for you there's also a WiFi-enabled model called
the "Assembled Adafruit Feather M0 WiFi - ATSAMD21 + ATWINC1500" but they're
quite pricey at US$36: small but more expensive than a Pi. I'm also exploring
the Circuit Playground from AdaFruit.

The other alternative I've looked into was going with a JavaScript OS using
the WiFi-enabled Espruino (https://www.adafruit.com/product/3514) which are
tiny, low powered and very cool. It's actually possible to install Python on
one of these:


so you'd have both JavaScript (as the OS) and Python. It has an I2C bus so
the Adafruit and Pimoroni I2C sensors could (in theory) run on it. This
would be very suitable for a micro-bot. I think I might try that one day.

Location Mapping ..........................................................

 > We have had some interest time-to-time in the club about using Bluetooth
 > and other RF mechanisms for indoor location mapping.  And we're aware of
 > some systems out there to facilitate that - for example this one which
 > appears geared for public venues - https://quuppa.com/ (not sure that
 > it's hobbyist friendly).

Thanks for that link. They do look a bit too official for my project. I'll
leave what is a rather long description of my bluetooth navigation project
to the blog...

 > We do need to up our game on the DPRG project blogging front - we've
 > been active but haven't published much about our projects except for
 > competitions and our monthly presentations.

I'm a bit surprised the DPRG doesn't have a wiki, as it would seem that
would be an ideal way to collect, document and provide ongoing access to
the collective knowledge of the group (which must be pretty broad and deep).

Communities & Organisations .............................................

 > In terms of typical DPRG projects, it could help to look at our recent
 > contests
 > - 2020 Fall RoboRama draft plans, https://www.dprg.org/roborama-2020/
 > - Full menu of contests we tend to pick from
 > https://github.com/dprg/Contests
 > and our YouTube channel which you've probably already found:
 > https://www.youtube.com/user/DPRGclips

With your encouragement I started blogging about the project, and for the
purposes of keeping notes started a wiki as well. But that ended up being
only a start...

We have some friends who have two daughters, 4 and 9 years old. The older,
Ellie, was very interested in my robot project and when talking with her
dad it occurred to me that I might start a robot group here in Pukerua Bay
(small town, population ~1500). Upon investigation there are no robot
groups anywhere near where I live, and no New Zealand based group that I
could find. On looking for a domain name for my new blog (and a potential
group) I managed to snag the robots.org.nz domain.

So I've (somewhat inadvertently) started the New Zealand Personal Robotics
Group (NZPRG). Ellie's dad talked to her local scout troop leader and we
may be able to secure their scout lodge for monthly meetings. I'll meet the
leader within the next few weeks to discuss this further. It turns out the
Pukerua Bay primary school has an active STEM program so I'll likely also
approach the principal to see if there's interest there.

I've started blogging about the KR01 robot project at:


The NZPRG sites are at:

    https://robots.org.nz/                 (blog)
    https://service.robots.org.nz/wiki/    (wiki)

I've never started a group and I have no idea how to bootstrap a community,
but it seems we have a (modest) start, and see what happens in the new year.

Thanks very much for the references and the welcome.

Happy holidays,


Murray Altheim <murray18 at altheim dot com>                       = =  ===
http://www.altheim.com/murray/                                     ===  ===
                                                                    = =  ===
     In the evening
     The rice leaves in the garden
     Rustle in the autumn wind
     That blows through my reed hut.
            -- Minamoto no Tsunenobu

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