#robotics Logs

Aug 27 2020

02:59 AM Jak_o_Shadows: srk, yeah, fair. I'm not overly familiar with the variants
03:05 AM srk: Jak_o_Shadows: there's like 2000 variants :D
03:07 AM srk: that's what I'm trying to reveal with clustering as well
03:07 AM * veverak went completely different direction
03:07 AM veverak: one chip, one chip to rule them all and bind them
03:09 AM veverak: (got robot with potentially multiple MCU's (+-20) -> STM32G431KC everywhere)
03:09 AM srk: oO
03:09 AM srk: finally ST? :D
03:09 AM veverak: using ST for a long time
03:09 AM veverak: wait
03:09 AM veverak: (calculating)
03:10 AM veverak: last 3 years STM32 or NXP ? wild guess
03:10 AM Jak_o_Shadows: Package is too big, unless I went BGA
03:10 AM veverak: oh
03:10 AM veverak: yeah, I discovered attiny85 this month and want to use it too in some stuff, true
03:10 AM Jak_o_Shadows: The other option is surface mount connectors
03:10 AM veverak: Jak_o_Shadows: of what?
03:11 AM Jak_o_Shadows: https://pasteall.org/media/2/9/29821d95c2e07f7d18348abd946ef592.png
03:11 AM veverak: I mean, I am moving to BGA coz we got PCB owen here now
03:11 AM Jak_o_Shadows: Dunno what BGA
03:11 AM veverak: ah
03:11 AM veverak: that's small
03:11 AM Jak_o_Shadows: It's a chainable serial servo driver
03:11 AM Jak_o_Shadows: With an upgrade path to CAN
03:12 AM veverak: yah, got LQFP-32 now
03:12 AM veverak: but I have to BGA it to get more space on the board (24x24mm size borad)
03:12 AM veverak: or
03:12 AM veverak: UFQFPN
03:13 AM veverak: I mean, I was told that I can do that with a hand soldering
03:14 AM Jak_o_Shadows: LQFP32 is 1mm longer than the TSSOP20 I have
03:14 AM Jak_o_Shadows: Go the UFQFPN
03:14 AM Jak_o_Shadows: I reckon those are doable at home with the right gear.
03:14 AM veverak: hmm
03:14 AM veverak: I mean, I have uni lab. gear, so these are definetly doable
03:14 AM veverak: but I do not want my designs to require that level of gear
03:16 AM veverak: https://imgur.com/a/QM6KrCd
03:16 AM srk: like a hot plate?
03:16 AM srk: :D
03:16 AM veverak: no, owen, microscope and pretty good soldering sation
03:16 AM veverak: was allready fixing pisn _under_ the MCU with that microscope
03:16 AM veverak: microscope is <3
03:17 AM Jak_o_Shadows: LQFP is probably be where I would stop
03:17 AM Jak_o_Shadows: and 1.27mm pins
03:17 AM Jak_o_Shadows: Anything smaller than that got expensive pretty fast
05:17 AM veverak: 1.27mm pins are meh too
05:17 AM veverak: you can't find any for stackable headers
05:17 AM veverak: which can be solved by using 'smd' versions and putting them on both sides
05:17 AM veverak: but that takes a lot of place and is not win either
05:22 AM srk: veverak: what that board does?
05:22 AM veverak: srk: base board for everything
05:23 AM veverak: controlling servos/imus
05:23 AM veverak: pressure sensors on feet
05:23 AM srk: load cells?
05:23 AM veverak: but I will drop the "multiple headers" feature, I suspect I can use just the base board for 1/2 of the stuff and simple shields for the rest
05:24 AM veverak: srk: those are problematic (to find proper dimensions/properties)
05:24 AM veverak: I have researched 4 ways to measure pressure? it's in TODO to pick one and do it
05:25 AM Jak_o_Shadows: veverak, I'm planning on putting the bar type sensors as part of the legs
05:26 AM veverak: yeah, that too seems vallid
05:26 AM Jak_o_Shadows: and yeah, I can't say that I'm happy with the headers/connectors at all
05:27 AM srk: iirc you can get flexible straing gauge which can be glued to the part
05:27 AM srk: something like https://miro.medium.com/max/800/0*QzLWiHhi6Ic38yYm.jpg
05:27 AM Jak_o_Shadows: Yeah
05:28 AM Jak_o_Shadows: through you'd need to design the part you glue it to right
05:28 AM veverak: exactly
05:28 AM veverak: simple load cell that I could "just wire to my ADC" has certain appeal to it
05:33 AM Jak_o_Shadows: https://hackaday.com/2020/01/04/opendog-adding-force-sensitive-feet/ as much as I think opendog tends to be under-engineered
05:33 AM veverak: well, there should be a holy war on one topic
05:33 AM veverak: spiders or dogs?
05:33 AM veverak: :))))
05:34 AM Jak_o_Shadows: My plan is quadrapod, but with flexible spine
05:34 AM Jak_o_Shadows: But I have a hexapod to test out software and electronics
05:34 AM Jak_o_Shadows: and a stewart platform to test out control of the flexible spine
05:35 AM srk: Jak_o_Shadows: why under-engineered?
05:36 AM srk: like, compared to mini cheetah.. sure :D
05:36 AM Jak_o_Shadows: Too much iteration
05:37 AM srk: there are paths meant to be walked.. like realizing that CAN or differential buses are good for robotics :D
05:37 AM Jak_o_Shadows: I also mean the mechanical side
05:38 AM veverak: Jak_o_Shadows: flexible spine in what way?
05:39 AM srk: didn't watch the full series yet, his sonic the hedgehog robot series was fun tho
05:39 AM Jak_o_Shadows: veverak a 6 DOF actuator. Through I expect most utility to be within 2 DOF at a time
05:39 AM veverak: interesting
05:39 AM Jak_o_Shadows: Those 2 DOF being a rotation and a single translation
05:39 AM veverak: I thought about adding 2 actuators to the spine of the robot too
05:39 AM veverak: two rotations
05:41 AM Jak_o_Shadows: The idea is something like this for the guts - but smaller and faster: https://www.youtube.com/watch?v=ECR_AXm8g4Y
05:42 AM Jak_o_Shadows: and not actually upright? I think you can get benefits for a quadrapod
05:43 AM srk: looks like slow motion.. :D
05:43 AM Jak_o_Shadows: Yeah, i've never seen that robot move fast
05:44 AM srk: they should give it a sloth head instead
06:27 AM Jak_o_Shadows: For the smallish stewart platform I'm playing with, I can get like 8cm translation
06:27 AM Jak_o_Shadows: does come with some rotation, but still
06:28 AM Jak_o_Shadows: and a good +- 30 degrees rotation with little translation
06:38 AM veverak: hmm
06:38 AM veverak: damn it
06:38 AM veverak: I would like to bbuild it in free time sometimes
06:39 AM Jak_o_Shadows: I first did some of the software for this at the start of 2016
06:40 AM Jak_o_Shadows: Some poor finayl year uni student tried asking me questions about it the other week
06:40 AM Jak_o_Shadows: month