RIS 51515 HexaPlod Mk1

[Laid Back Koala]

This guy came into being from a challenge that I set for myself.  Was it possible to build a hexapod robot using just the parts from the RIS 51515 set?  It took a while to get right and many prototypes.  The parts limitation being the biggest headache.

HexaPlod Mk1 uses the alternating tripod walking method and is fully controllable for forwards, backwards, steering and tank turn walks.  He also demonstrates how to synchronise motor movements using word block programming.  If anyone translates any of this into Python, I'd would welcome the results as I'm only just getting my head around it.  I've used many languages so it looks familiar, but I've yet to explore and understand the libraries.  Also intrigued by the hub-to-hub library https://hubmodule.readthedocs.io/en/latest/hub2hub/?fbclid=IwAR0FsNoXblSZXMfXOhZMvc6GDSjIvgsb7hXY6lbrb4YXO20HqPJ2BHOmR34 .  So lots to learn.

The Building Instructions, a detailed Read Me and a couple of detailed word block programs are all in the zip file, downloadable via this One Drive link https://1drv.ms/u/s!Agv70JYmtXzNhMFlXl2cBZt0zL4aBg?e=v8rrOc .

I'd just received delivery of my Spike Prime and Expansion Sets near the end of this project (well current pause really ).  So been a bit distracted documenting this guy while I stared longingly a a couple of large boxes.  I'll likewise be even more distracted now I've opened them .

Hope you enjoy HexaPlod Mk1.  Now back to Spike for  while...

[Laid Back Koala]

Four videos of the 'Plod in action:

 

 

 

The hub seems to create a bit of audio interference on the videos too.  Will have to experiment a bit.  This is the first time I've tried videoing anything before, so apologies if they're not up to scratch.

Edited August 18, 2021 by Laid Back Koala
Replaced One Drive link with YouTube links

[Mr Jos]

Why don't you upload your videos to Youtube? Then you can directly link them here and viewable on this page, much easyer, and more people will watch it.

[Laid Back Koala]

Thanks Mr Jos - original post edited accordingly.  It's years since I last dabbled in YouTube 

[Mr Jos]

Well done, funny robot to look at how it makes a turn, would it be possible to speed up the walking or are the motors already working on their limit?

[Laid Back Koala]

4 hours ago, Mr Jos said:

Well done, funny robot to look at how it makes a turn, would it be possible to speed up the walking or are the motors already working on their limit?

The lifter motor (middle legs) is at 80% speed, the outer leg motors are at 40%.  Each is geared down 3:1.  This gives enough power to lift the heavy body.  Without the gearing, the lifter motor struggles.  I kept the outer legs at half the speed of the middle legs to explore synchronising all three motors, which I'm still working on but a bit distracted by the arrival of my Spike Prime sets.  The lifter motor moves from -180° through +180°.  The outer leg motors move from -90° through +90°.  So for the same time to complete a cycle, the outer motors need to move at half the speed of the lifter.  This is only critical when trying to synchronise all three motors.  With only the outer leg motors in sync (the demo program) this is not necessary and, in theory, you can increase their speed up to max.  However, the legs start to slip if it's too fast!

The whole point of this robot was that it can be built by anyone who only has the RIS to build with.  The design is far from ideal and can be built a lot better using extra Technic pieces.  But not everyone has that luxury and I wanted to give any newbies something different to think about.  I now have the Spike Prime sets, which gives me two of the larger motors.  So I will be exploring a more suitable build using my vast store of Technic bits.  (I started collecting Technics in 1979.  Back then, all beams had studs and there were no friction pins  !  Incidentally, parts from back then still fit perfectly and still 'clutch' each other well.)  The speed can be increased a lot by just extending the leg lengths out more to give a greater distance per stroke.

If you download the zip file, the Read Me has full details of the strategy behind this guy.  Plus the calibrator and demo programs and building instructions.  Apart from programming, there's not much more that can be done to improve things given the "RIS only" constraint.  I put a distance sensor on him, but haven't programmed that yet.

[oracid]

Thank you for sharing this great work.

[Gimmick]

Realy cool, I like it.

Since this is only using 4 ports it should work with a technic hub, too. And thanks to your instructions, you can certainly convert the model to other motors from technic-world :).

[Laid Back Koala]

2 hours ago, oracid said:

Thank you for sharing this great work.

Thanks oracid.  Love your web site.  I'll have to spend a few pleasurable hours exploring it .

1 hour ago, Gimmick said:

Realy cool, I like it.

Since this is only using 4 ports it should work with a technic hub, too. And thanks to your instructions, you can certainly convert the model to other motors from technic-world :).

I don't know very much about the Technic Powered Up hubs (yet).  The motors and sensors are compatible with the Mindstorms/Spike hubs but that's as far as I know so far.  The fact that they all communicate via bluetooth is encouraging.

The model can certainly be improved and constructed way better than HexaPlod as he was limited by what was in the RIS.  Just for fun I'm speculating whether the same thing can be done with the Spike Prime sets.  Anton's Ladybug is one example but it lacks the ability to vary the step length, 

When we moved house a few years back I was banned from Lego "Until a few things get done around the house" .  I did manage to sneak in the Crawler Crane and Bucket Wheel Excavator which are still waiting to be stripped for parts.  Plus my ageing Technics, Cybermaster, Scout, Manas  and RCX brick pit carefully sorted and stored away.  Somehow life just seems to get in the way...

[ninoguba]

Nice, looks like this can be a beetle =)