#robotics Logs

Feb 17 2019

05:00 AM veverak: lol
05:07 AM Tom_L: a friend had one of those
08:52 AM veverak: damn it
08:52 AM veverak: I am doing something wrong with the PCA9685
08:52 AM veverak: thought that by now I know how to work with it :/
10:10 AM goppo: i'm trying to build a 4-wheel rover that can turn tight corners. is there a guide for synchronising the wheel speeds?
10:11 AM Mikeee: you mean for skid steering?
10:11 AM goppo: oh right. is that what it's called
10:11 AM Mikeee: you could tie it in with an accelerometer if you wanted
10:11 AM goppo: is it very bad for the tyres?
10:11 AM Mikeee: not usually, unless you do it constantly
10:11 AM goppo: it's for outdoor usage
10:11 AM Mikeee: in dirt it's fine
10:12 AM Mikeee: on concrete, just avoid soft tires
10:12 AM goppo: how does the accelerometer come to play?
10:13 AM Mikeee: skid steering is "turn on a dime" if you have a human controlling it, like with hydrostatics. But a computer won't automatically know when one side is getting slightly more traction, and you may move slightly to the side instead of just turning
10:13 AM Mikeee: an accelerometer can sense that slight drifting and compensate, like a human operator riding a lawn mower would
10:15 AM Mikeee: i used something similar in a robot I made for cleaning drain pipes. If the water started moving it backwards, it could compensate by rolling a bit in the pipe for better traction
10:15 AM goppo: right
10:19 AM goppo: is skid steering easier on 6 wheels than on 4 wheels?
10:19 AM goppo: most of the (robotic) ones i've seen use 6 wheels
10:20 AM Mikeee: it'd be the same
10:21 AM goppo: ok
10:26 AM goppo: Mikeee you mentioned skid steer can make you move to the side rather than just turning, but how is that possible?
10:27 AM goppo: you mean when drifting? but pivot steering can drift too
10:28 AM Mikeee: i meant it can result in it, if the terrain is not uniform
10:28 AM Mikeee: not that it'd be a desired function
10:28 AM goppo: ah
10:28 AM Mikeee: if you want lateral motion, use omnidirectional wheels
10:29 AM goppo: oh, no. skid steering is good enough
10:29 AM goppo: now i need to find a good controller
11:33 AM goppo: i'm thinking of using hoverboard wheels in my little rover. unfortunately they seem to come with a round shaft. how can a round shaft be fixed to the platform? https://endless-sphere.com/forums/viewtopic.php?t=81756
12:43 PM Mikeee: doesn't look round to me
12:43 PM Mikeee: looks keyed with a flat side
07:45 PM rue_shop3: oo whats up
07:45 PM rue_shop3: veverak, i2c, .. whats it?
07:46 PM orlock: i'm thinking about making a powered hacksaw chop-saw thing
07:46 PM Mikeee: like a sawzall?
07:47 PM rue_shop3: oh its the crap pwm controller
07:47 PM rue_shop3: veverak, lets see your code dude
07:47 PM orlock: yeah, except bench-mounted
07:47 PM Mikeee: so a jig saw
07:49 PM orlock: https://www.thingiverse.com/thing:1555072 https://www.thingiverse.com/thing:1988766
08:03 PM Tom_L: cute
08:30 PM goppo: Mikeee you're right
09:16 PM mrdata- is now known as mrdata_
10:07 PM mun: i'm trying to build a self driving rover with cheap hardware. is ROS an overkill for path finding and tracking?