I've been playing around with Nybble, trying to diagnose some traction problems, and making plans for trying some new gaits later. To work on gaits, though, I'm thinking I'll need a stand that can support Nybble and let me load up any frame of a pose over serial. ( I'm not sure if there's a command for that already, but easy enough to write if not; the problem is making a stand! ) I could use cardboard, or wood, but then thought maybe I could just bend a coat hanger into shape. I drew up a rough idea of what I thought might work and then started bending a coat-hanger with pliers.
I'd bend a bit, hold it next to cat then bend some more.
But it started to seem like it wasn't going to work but after bending and bending and bending, I got it to look like this:
There wasn't enough wire to complete the far side of the stand, but maybe if I cut it... and then mount it onto a board later?
Slowly taking shape. literally "taking shape" :P
I don't have a clear picture, but, before nailing the hanger to the board, I wrapped some electrical tape around the top, just to provide a bit of insulation and cushion.
First time the little level on my pen came in handy!
I've been trying to identify a problem my Nybble's had with skidding, and the first time I ran it on the cradle it was clear... there's a slight stutter with the left rear leg ( aha! I suspect I've been a bit too rough with Nybble :P
To be sure it was the servo and not code, I figured I'd swap out one of the head servos for the rear thigh. ( continued ... )
Another clip showing the stutter ( left rear leg on far side ):
So I pulled off the servo for the head tilt and swapped that in for the thigh, just to verify, and the gait looks pretty good! :D
So I think later this week I'll dismantle and move the tail servo to use as the left-rear thigh. Then I need to revisit the variable speed Nybble code by Mark DeNies with the new thigh! :D I've got that code running on Nyboard V1_0, but results were affected by the leg skidding problem. Now that that's corrected I'm excited to try that code again... next weekend's project! :D
Hey, it's a very well documented process of how you found a problem, designed tools, validated your preassumptions, and found a solution by moving the best parts to the most needed place. It's an enjoyable workflow to read through.
I saw the knee servo's jittering in the first video. I'm not sure about the cause but it seems not significant when swapped to the head. How long have you been using the servos, like the accumulated running time by hours?
Hi Rongzhong, Thanks! :) I've been having great fun with Nybble the past few weeks! And still a bunch more ideas to try coming up :) So far I don't think I've used the servos too many hours. I built the kit at start of February and have changed the batteries maybe 7-8 times? ( I'm estimating high. Could be more like 5-6 but maybe I'm deceived, you don't notice when having fun). But I have been a bit rough with Nybble too; I probably need to start playing a bit more gentle (and keep her out of the snow :P Troy ps - I am so impressed with Nybble's design: the 3D puzzle design, the Nyboard, the code... it's all brilliant! Thanks Rongzhong! I been wanting to play with walking robots for years (decades even) and this is great fun :)
I came across your post a while ago and today I wanted to make my own coathanger cat stand only to find out I have no hangers of this type :)