#robotics Logs

Apr 04 2019

02:52 AM Jak_o_Shadows: veverak, the way I see it, you only want force feedback for one main reason - to see how much you can use that appendage
02:57 AM Jak_o_Shadows: Position feedback tells you if you're achieving what you want, but not much about why
02:57 AM Jak_o_Shadows: Which is one of the reasons why I like sensors not just on the feet - that doesn't tell you much if it's getting blocked somewhere else
04:32 AM veverak: Jak_o_Shadows: I also want to know how stable it is
04:32 AM veverak: for that you need to know foot pressure of each leg and actual _real_ configuration of the robot
04:32 AM veverak: hmm, you definetly need IMU to know where gravity is
05:07 AM Jak_o_Shadows: Yeah, i was assuming a single IMU somewhere
05:08 AM Jak_o_Shadows: I'm not quite so sold on multiple IMU
05:08 AM veverak: Jak_o_Shadows: it's one of the things I am curious about
05:09 AM veverak: if multiple imus merged with kalman can bring better results
05:09 AM veverak: assertion is that they _do not_ have same orientation
05:09 AM Jak_o_Shadows: Mounting rigidly wrt each other?
05:10 AM veverak: exactly
05:11 AM veverak: Jak_o_Shadows: 3 imus, Y axis of first, X axis of second, Z axis of third aligned
05:11 AM Jak_o_Shadows: Yeah. I dunno
05:11 AM Jak_o_Shadows: seems like you could just buy a nicer IMU.
05:11 AM veverak: you alwasy can
05:11 AM veverak: I am just curious about what effects it can have
05:11 AM veverak: :
05:11 AM veverak: :)
05:12 AM veverak: veverak: maybe you should finally buy that pack of 5 IMUs from aliexpress
05:12 AM Jak_o_Shadows: aha
05:13 AM Jak_o_Shadows: Yeah. I feel like you could definitley improve things with multiple IMU's, assuming they are rigid enough
05:13 AM veverak: yup
05:13 AM veverak: Jak_o_Shadows: I assume that the IMU has some deffeciencies
05:13 AM veverak: Jak_o_Shadows: and I assume, that they are not equally distributd around the "sphere" it can measure
05:13 AM Jak_o_Shadows: Yeah.
05:13 AM veverak: so, when you take 3 spheres, each rotated differently, you could reduce the error
05:13 AM Jak_o_Shadows: I agree
05:14 AM veverak: and maybe you do not need kalman , just avg. val is good enough
05:14 AM veverak: :)
05:14 AM Jak_o_Shadows: I was about to say that
05:14 AM Jak_o_Shadows: averaging is unlikely to make it worse
05:14 AM Jak_o_Shadows: And with i2c sensors or something, it would probably be reasonably easy to actually do as well
05:14 AM Jak_o_Shadows: wirigin the most difficult part probably
05:14 AM veverak: yup
05:15 AM veverak: and I have 3d printers round which are reasonable precise
05:15 AM veverak: so printing one part that holds all 3 of them should be doable
05:15 AM veverak: although, rather than expecting them to be perfectly positined
05:15 AM veverak: it may be better idea to do some autocalibration of the relative positions
05:15 AM Jak_o_Shadows: It'd be super duper interesting to try to use them to figure out flexing in the thing.
05:16 AM veverak: like position them at different parts of the robot/
05:16 AM veverak: ?
05:26 AM Jak_o_Shadows: Yeah. and then see if you can figure out how it is flexing
05:26 AM Jak_o_Shadows: like, nothing is entirely rigid. Not even steel.
05:27 AM Jak_o_Shadows: It'd be interesting. I think you need more than a couple of discrete points, and I think you need to trust your sensors more though
05:28 AM veverak: exactly
05:28 AM veverak: the cheap IMU's may not do the trick
08:29 AM rue_bed: dont almost all imu need a fancy filter?
08:34 AM veverak: dunno
08:34 AM veverak: have yet to master them
01:12 PM s34n: I'm looking for some magic form of tachometer that doesn't use hall sensors or induction. The only observable is power.
03:29 PM deshipu: how does one observe power?
03:30 PM polprog: that would be a crap tacho, a stuck motor takes power as well
11:46 PM Wayfarer: http://www.cs.cornell.edu/Info/People/raman/publications/colored-paper.html
11:46 PM zhanx: Wayfarer, is back
11:46 PM zhanx: dude pm me
11:46 PM Wayfarer: ?
11:47 PM zhanx: you want an arduino board?
11:47 PM zhanx: you have a laptop etc
11:48 PM Wayfarer: Im looking at esp430, a couple others
11:48 PM Wayfarer: I rather dont care for the arduino brand
11:50 PM zhanx: well you have a pm
11:51 PM Wayfarer: Im good. thanks though, you have the source where you got it?
11:52 PM zhanx: no that is a business thing
11:53 PM zhanx: I also have photon particles if you want some i am send 2 to rue_bed
11:53 PM zhanx: i have 30
11:53 PM Wayfarer: idkwti
11:54 PM zhanx: i can solve that
11:55 PM zhanx: https://www.sparkfun.com/products/13774
11:55 PM zhanx: each has https://www.sparkfun.com/products/13628
11:56 PM zhanx: and a https://www.sparkfun.com/products/13626
11:56 PM zhanx: wife wants me to clean out my stuff