Tag Archives: build

Building the quad A1

Now that I have a bunch of the mk2 servos set and ready to go, a new leg design, a new power distribution board to power them, and a raspberry pi3 hat to communicate with them, I built a new quadruped!  I’m calling this the mjbots quad A1, since basically everything is upgraded.

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After I initially assembled the new legs onto the chassis, I realized I had the geometry slightly off and there was some interference through part of the shoulder rotation.  I made up new printed parts and replaced everything in front of the camera.  Thus, watch some high speed robot surgery:

The quad A1’s first job is to validate the new moteus controller in the quadrupedal configuration, after which I’ll use it as the primary development platform to get all my gait work done.

 

Pre-production mk2 servos

To build a second demonstration quadruped and to generate some development kits, I’ve built up a set of 20 of the mk2 servo.  The production process is working out fairly well, in fact slightly better than I had predicted for overall cycle time.  The servos so far are coming out great, moving smoothly with full power.

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Shafts inserted into the planet input
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Output bearing on the planet outputs
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Planet output and internal gears onto the front housing
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Rotors with bearings and sun gears
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Stators installed
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Planet inputs with planet gears
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Planet inputs installed
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Back housing installed
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Moteus controller soldered
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All buttoned up

Now I need to test these on a quadruped!

 

All parts for pre-production mk2 servo in house

I’m planning on building up a set of mk2 servos to test them on a quadruped and make some development kits.  As of now, I’ve got all the materials in house for the build and many things partially assembled!

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A bunch of back housings
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Back covers post-brushing
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A bunch of planet inputs
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A test of the final finish of the outer housing
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Bunches of front housings and planet outputs

Building the moteus controller dev kits

As mentioned previously, I’m releasing moteus controller development kits to a few lucky beta testers.  Building these wasn’t too hard, but was my first foray into low-volume production for someone who wasn’t myself.  Here are a few pictures of the build:

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Machining the bracket
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A bunch of CAN cables
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A motor mounted on the bracket
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Mounted into the “desk stand”
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A bunch of brackets and stands
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STM32 programming cables
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Motors getting ready for installation
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A number of assembled kits

A big thanks to all the beta testers!  With the next revision of the controller, I’ll continue to have a development kit with roughly the same properties for those wishing to get started in an easy way.

If you have devkit envy, you can get a little fix watching this video showing how to set it up and use it.

 

Lots of frameless stators and rotors

While gearing up to make some dev-kits followed by a pre-production run of the moteus servo mk2, I recently received a bunch of frameless rotors and stators.

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It’s almost taller than me!
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Some stators
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A rotor

As with the other custom items, I’ve got some spares of these for sale at shop.mjbots.com if you’re building along with me!

Now it’s time to start building some servos!

 

moteus servo mk2: Functional test

Now that I have at least one functioning version of each of the pieces made for the moteus servo mk2 (planet input, outer housing, front housing, and back housing), I integrated all of them together into a functional prototype.

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A bunch of pieces
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Front housing with stator, internal gear, and planet output installed
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Planet input, gears, and shafts installed
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All put together… a bit on the heavy side for now

And finally, spinning it up!

Ramping up for moteus servo mk2

Some time ago I put in orders for all the long lead time items on a second version of the moteus servo.  This is primarily aimed at improving the manufacturability and reliability, along with some minor performance improvements.  I’ve now got at least samples of all the long lead time parts in house!

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Loads of bearings
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A lot of custom gears
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A sample batch of custom rotors and stators

Coming up soon I’ll post a more detailed design update on the servo.

 

quad A0 chassis v2 – final assembly

In the last post in this series, I conducted a fit test on the new chassis.  After my ignominious belly-flop, I now had a more urgent need to complete the switch.

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A busted robot
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An even bigger close-up

The chassis cracked in the corner, completely separating.  Doing anything more with this chassis was likely to result in many more things breaking very quickly.

Build process

So, here are the photos as I put everything together.

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Raspberry pi attached
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All the wiring extracted
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Half the legs off the old chassis
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Legs re-attached to new chassis!
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Battery stud and wiring re-installed
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The power board installed
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Bottom plates installed
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Upright with untidy wires
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All set for testing!

Next up is continuing to try and get pronking working!

 

Full rotation quadruped build continued

The next step in (re-)building the quadruped with a full rotation leg was getting all the motors ready.  I had to first install reinforcing rings on 6 of the motors:

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My epoxying station
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4x gearboxes with reinforcing rings installed

Then, I needed to lengthen the power leads on 3 of the motors to serve as the lower leg joint.

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Motors with longer power leads

Then I had to assemble all the new legs:

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Upper leg joints mounted
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Lower leg joints mounted
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All three remaining legs built

I mounted them all to the chassis:

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All the legs!

And then re-installed the battery stud and “resting” feet:

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Next up, will be actually powering them and getting it to walk!

Stripping the coaxial quadruped for parts

To switch to the full rotation gear design, I needed to get all my gearbox motors, some bearings, and a lot of other bits and pieces disassembled and ready for re-use.

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The remaining 3 non-broken legs from Maker Faire

Taking everything apart took a surprising amount of time, nearly a full day.  Each leg resulted in quite a collection of fasteners.  Seeing them all in one place made me realize how complex this has become!

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One leg’s worth of parts

I’ve also got the full set of parts printed for the full rotation legs:

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Now I just need to get to assembling and reworking to get them all installed!