#robotics Logs

Apr 28 2020

12:41 AM zhanx_ is now known as zhanx
02:40 AM Peppi^: hello
02:40 AM Peppi^: rue_mohr around?
02:41 AM zhanx: rue_bed, Peppi^
02:41 AM Peppi^: it's late in Canada lol
02:50 AM Jak_o_Shadows: time zones eh
03:03 AM rue_mohr: hi
03:03 AM rue_mohr: Peppi^,
03:05 AM Peppi^: oh hi
03:05 AM Peppi^: rue_mohr, zhanx told me to find you :) can I PM you?
03:07 AM rue_mohr: sure
03:24 AM LarchOye is now known as Guest72062
03:54 AM mrdata: it isnt late; it's early
04:01 AM zhanx: mrdata, wrong timeline
04:01 AM mrdata: no?
04:01 AM mrdata: zhanx, i am in canada also
04:04 AM Jak_o_Shadows: It's lateish on the other side of the world in Australia, so must be early there
04:36 AM LarchOye is now known as Guest34183
01:30 PM veverak: \o/ I can calculate jacobian for my legs
01:30 PM veverak: (jacobian of FK
01:30 PM veverak: now to inverse it an solve IK <3
06:08 PM veverak: so, jacobian works, somehow
06:09 PM veverak: except that it starts by making bigass movement to nowhere and than approaches the target pos
06:09 PM veverak: (numerical solution, so iterative algo to find the angles)
06:09 PM veverak: the way it approaches the function looks like log(x)
06:09 PM veverak: hmm
06:18 PM veverak: fixed \o/
06:18 PM veverak: seems like this numerical solution needs to limit the change per one step to some value
06:21 PM veverak: oh, yeah, this is known sideeffect of pseudoinverse of the jacobian around singularities
06:28 PM veverak: wow
06:28 PM veverak: this shit can actually handle tree-shaped arms
06:28 PM veverak: (imagine: fingers)
06:42 PM veverak: sooo
06:42 PM veverak: 3DOF arm, 25 length
06:42 PM veverak: target pos: { 20, 0, -5 }
06:43 PM veverak: solution after 70 steps: { 20.0001, 0, -4.9997 }
06:43 PM veverak: that's pretty good
06:45 PM veverak: now same precision after 50 steps
06:45 PM veverak: hmm this can be improved a lot
06:54 PM veverak: let's turn it around -> make stups until error < 0.1 (which on 25 length is pretty good)
06:54 PM veverak: -> 17 steps
06:54 PM veverak: \o/
06:55 PM veverak: increased step size a bit and down to 12 steps, good enough, so let's move to another problem :)
11:56 PM rue_mohr: hi
11:56 PM rue_mohr: cool! whats the robot!\