Hey everyone,

I'd like to show you my very very first attempt at a MOC, using pieces from the Liebherr excavator. My main source of inspiration for this comes from the legendary manipulator crawler MOC which I very much enjoyed building. However, I felt like I wanted something a bit smaller and more agile to serve me coffee in the morning or mop the floor (disclaimer: it can't really do any of this yet :P). 

The vehicle features 2 independently driven tracks (1 L-motor each), a panning tower section (1 XL-motor), an arm that can move up or down using a simple parallel lever system (1 L-motor and 2 linear actuators), and a scissor-like gripping mechanism ( XL-motor and a tiny linear actuator) that can rotate freely (1 L-motor). The motors are controlled using 2 hubs: the one in the platform controls the first 4 motors mentioned, while a second hub in the tower section handles the gripping arm retraction and rotation. 

Overall, I'm quite satisfied with the base (especially the cover for the hub) and the gripping mechanism. The tower section and arm are still WIP. These are the things I'd like to improve:

• move gripper motors closer to the tower for better weight distribution and to reduce fatigue on the actuators
• smarter arm lifting mechanism with increased range of motion
• make the second hub more accessible

Here are a few shots (please let me know if I'm breaking any rule with regards to posting pictures etc).

I know that the idea is not the most pioneering one but I have to start from somewhere, ehe. 
Hope you enjoyed it, looking forward to feedback and suggestions for improvements!

Edited February 5, 20223 yr by miccio
updated image links

Strange, that Your pics doesn't emebed automatically

For me works

5 hours ago, Jurss said:

Strange, that Your pics doesn't emebed automatically

Yeah, I also thought it was weird. I now added BBcode thumbnails with links to the original files.

So, time for a quick update!

I redesigned the tower and the horizontal part of the gripper arm.
This allowed me to put the battery pack and one of the gripper motors somewhere where they can actually counterbalance the weight of the gripper

In order to move the gripper motor, I had to introduce a system of axles.
I'm not entirely happy of how it turned out (there is a bit of backlash) and I still haven't secured the motor, but here is a preview:
   

Furthermore, I changed the mechanism responsible for lifting and lowering the arm.
This new system doesn't have any hinge, relies on gravity to lower the arm, and looks a bit silly.
However, it provides a wider range of heights:

I also moved the motor driving the rotating platform so that it sits vertically:

 

Feedback and suggestions are very very welcome! :)

Very cool. I like it.  The 42100 is the set that pulled me out of my dark ages and sent me on my journey building my robot arm.  Having seven motors to play with certainty begs you to make something like this.  I ended up on a quest of iterative improvements every time I discovered new parts or new techniques that could help make it better.  Have fun tinkering!

Thanks, Glaysche. I presume that I am also going to follow that path (or rabbit hole) :P 

Do you have a link to your robotic arm?

Looks good! I really like the compact design. It is definitely a good solution to put the battery box on top of the arm, so it can be used as a counterweight.   

51 minutes ago, miccio said:

Do you have a link to your robotic arm?

Yeah: https://rebrickable.com/mocs/MOC-84097/glaysche/6-axis-robotic-arm/#details

 

There was also a Eurobricks topic that's linked from the Rebrickable page.

What an amazing design! Very neat and ingenious. I might have a look at your stud.io files to learn a few tricks.

36 minutes ago, miccio said:

What an amazing design! Very neat and ingenious. I might have a look at your stud.io files to learn a few tricks.

Thank you!  Please do have a look.  We can all learn from each other.

Oh, speaking of that, you mentioned backlash in your most current design.  That has been a challenge for me in my design.  A few things have helped me.  First, for long axles, it's often better to use connectors like 59443 or 42195. They are more rigid than axles.  The second trick I've used is to have multiple redundant gear trains.  You can then "pre-tension" the gear train by assembling it one or two teeth's worth of tension built in.  That can dramatically reduce gear related backlash.  Finally, I've found that by gearing down as late as possible in a gear train will reduce backlash.  This keeps more of the gear train with lower torque.  Any backlash in the low torque, high speed portion of the gear train is reduced by whatever gearing down you have at the end.  I use this to drive the last two axes at the end of the arm.  I actually gear up the motor for the long gear train, only to gear it down at the end.

11 hours ago, Lukes_Brick_Studio said:

Looks good! I really like the compact design. It is definitely a good solution to put the battery box on top of the arm, so it can be used as a counterweight.   

thank you! The idea was to build a tinier version of the manipulator crawler (i.e. this big guy) :) Unfortunately the battery box is not sufficient to balance the arm, but it's definitely a first step! I would place further on the opposite side but the motor cable is too short.