Hopper Stabilization Hardware Progress

 More little drone motors, flywheels, and motor drive mounting brackets:

New MJF printed structure to hold everything:

This is almost everything, shooting for 1kg total when it's done, not much left for the protective shells, foot, and control PCB.

Balancing Leg

It balances!

The inertia changes significantly as the "body" moves up and down the leg - for the controller, I got feedback gains with LQR for the maximum and minimum extension cases, and linearly interpolate between those gains as the leg extends.

Leg + reaction wheel doing stuff

Running off a bench supply and offboard micro, controlling with a joystick.  There's an IMU attached too, so hopefully soon it'll be doing some 1-DOF balancing:

Reaction wheel motor assembly

Reaction wheel assembly

Still needs a motor, of course, but it's taking shape

Someone asked what the step on the inside of the reaction wheel was for:

Reaction Wheel Mount Op 1, Pulley Weight Reduction

 

Reaction Wheel

Back to making shiny things

Mini Cheetah Clone First Test Drive

 One of the Chinese mini cheetah clone manufacturers was nice enough to send me one.  Stay tuned for a  detailed (non-destructive) teardown.

First outdoor tests of the screw mechanism!

 Gremlins eradicated - USB hubs are  bad, don't use them:

"Only" ~3.3 meters in this test - not maxing out the motor/mechanism yet, there's still some motor control tuning to do.  And probably another round of transmission ratio optimization once the actual robot mass and inertia get finalized.

Finished Test Fixture

A robot-weight steel puck:

Test setup outside, before being beset by electrical gremlins:

Hopper test fixture

Not done yet, but almost ready for some high-power testing.

 

More Screw Mechanism Testing

 Now controlled over CAN and USB, using a gui based on the espresso machine software

The the USB communication plus Python GUI gives me nice live-plots and logs.  Here's a plot of the fast position steps:

Screw moving under power

 

Guide Rollers

Putting the lathe to work:

Another weird part

Turning off the fixturing boss from milling:

Undercut boss machining:

Foot Mechanism Prototype

 Quick and dirty prototype of a passive foot pitch mechanism:

CAD cross section:

To make a return spring I flattened the end of a 1mm spring steel rod and drilled a 1mm hole through the end for a dowel pin axle:

A drilled out screw acts as a guide bushing for the spring: