[Dprglist] Recommendations for Robot Platform

[Carl Ott]

Doug,

Great info!  Seems there is always something new to learn :)

Judging from this survey of the pretty big DPRG d-list - and knowing how
much people on this list scour sourcing options -  There seems to be a
trend...  Tons and tons of options out there, but nothing 'entry-level'
that comes with encoders, which strikes me as a big gap. These
off-the-shelf kits are all missing a critical foundational stepping stone.

I'm gonna suggest that in 2020 we build on what DPRG has learned between
the 2016 club robot, the 'build-more-robots' series, and even this year's
Donkey Car foray. The concept swirls around something / somewhere between
those three platforms in cost and capability - but something where a
reliable mechetronics platform can be programmed pretty-much out of the box
- something that gives easier first steps for those with primarily software
backgrounds. For sure let's chat in person as DPRG plans 2020!

- Carl



On Sat, Nov 23, 2019 at 9:43 PM Doug Paradis <paradug at gmail.com> wrote:

> Carl,
>>
>>     One of the most frequently asked questions by hobbyist roboticists is
>> "How can I make an inexpensive robot that I can grow with?". This was the
>> quest pursued by the DPRG 2016 Club Robot design. This design also had the
>> mantra that it would be built using "goodish" parts that would not need to
>> be replaced.
>>
>>
>>
>>     A lot was learned from the 2016 Club Robot, and I think that for a
>> robot of its size it is a good design. With its separate back and front
>> plate assembly feature it is a very configurable. The integral motor cage
>> assembly insures good alignment between the motors, making its’ tracking
>> very accurate.  The original design uses an Arduino Mega as the main
>> processor, which allows beginners an easy entry point to get started. With
>> David Anderson's (and Ron Grant) STM32 Nucleo breakout controller board,
>> the robot can be upgraded to ARM processors without extreme heart failure.
>> Another processor board configuration that includes a Raspberry Pi board is
>> the Pololu A-Star 32U4 Robot Controller SV with Raspberry Pi Bridge. The
>> chassis design, BOM, and a starting code base is available on DPRG's
>> GitHub. There is also a series of videos to show how to build it in its
>> original configuration. The motors have encoders.
>>
>>    The biggest issues with the 2016 Club Robot are:
>>
>>    1.  The open source code base that we have on GitHub uses
>>    David's cooperative scheduling multitasking system, which is not exactly
>>    beginner friendly. It is powerful and not overly complex, but I admit that
>>    it can sometimes cause problems when troubleshooting. However, this issue
>>    could be fixed by adding an alternate code base that didn’t use the
>>    cooperative scheduling.
>>    2.  The laser cut chassis is not easily obtainable for people without
>>    access to a laser cutter. Club members can always have one of the DPRG/DMS
>>    members cut one for them for a nominal cost. Laser cut services are also
>>    available. Note: You need to make sure your material thickness is the same
>>    as the design.
>>    3.  The original design's front plate (front halve of robot) could be
>>    simplified. Everyone modifies it. I would recommend a special purpose front
>>    plate be created based by the roboticist for the desired primary task of
>>    the robot.
>>
>>      I am currently working on a smaller (~6" wheelbase) and simpler
>> robot that utilizes features from the 2016 Club Robot design. Its
>> controller board is a Raspberry Pi 3A board with a Pololu A-Star 32U4
>> Robot Controller SV hat. This provides motor controllers and a 32U4
>> (Arduino compatible) processor for real time sensor processing. I plan to
>> use the Rpi mainly for AI and vision processing. It is powered by the
>> 3500mAh 18650 batteries that you told me about. I want to use this robot
>> for testing Donkey Car code, and as my Challenge LF robot (a different
>> front assembly). It uses DFRobot metal gear TTmotor motors with encoders,
>> which I purchased from Mouser. If you are interested let me know.
>>
>>
>>
>>     There are several off the shelf robot kits that have potential, but
>> lack one or more features. I have looked at the kits made by Sunfounder
>> (see sunfounder.com or Amazon), they are like a host of kits coming from
>> China and elsewhere. The price for these kits is from about $70 to $130.
>> They look like they are well thought out, but they are limited by their
>> cost constraints. It also depends on what you want to do. They almost
>> always lack encoders and use TTmotor TGP yellow motors. Pololu offers kits
>> that use "micro" gear motors, these motors are fine for small robots and
>> can be had with encoders. The Pololu robots also have excellent
>> documentation. I just personally don't like their chassis as general
>> robots, but I do own 2, a 3pi and a Balboa.
>>
>>
>>
>>     I would be interested in your reason for exploring robot learning
>> platforms. If you are looking at STEM activities, I think the Vorpal
>> Hexapod robot (search Thingiverse) would be worth considering as a starting
>> point to generate interest in robots. If you want a more traditional
>> differential robot design, the cheapest way is still the Amazon kit we used
>> in the "Build More Robots" training series.
>>
>>
>>
>>     Let's talk at RBNO.
>>
>>
>>
>> Regards,
>>
>> Doug P.
>>
>>
>>
>
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