#robotics Logs

May 25 2018

04:22 AM z64556 is now known as z64555
01:51 PM Tom_itx is now known as Guest1963
01:52 PM divxdude: sup robots
01:55 PM divxdude: i want my RC mower to run the cut blade on a 12v car starter but is the ESC fails the mosfets could short and the starter flys apart from over rev
01:55 PM divxdude: so like an audio rpm analysis for safety?
01:56 PM divxdude: the sound pitch of a motor tells the rpms no?
01:57 PM divxdude: programmed to cut the solenoid
01:58 PM divxdude: all these 36v 48v 80v mowers suck
01:58 PM divxdude: they are trying to outrun DIY'er that will make it run on a car battery
01:58 PM divxdude: battery pimps
01:59 PM divxdude: a 12v motor can cut the grass as good as any
03:25 PM z64555: audio? no
03:25 PM z64555: monitor the amps the motor is pulling
03:27 PM z64555: Voltage to the motor controls the speed of the motor, while current tells us how much force it is trying to do
03:28 PM z64555: could maybe use a variable buck converter to control the ESC, but that would be redundant as that's what the ESC is essentially doing
03:29 PM z64555: I'm not familiar with the details of car starters, but that's the general info about electric motors
05:27 PM SpeedEvil: divxdude: Or just don't, and use a brushless motor.
05:28 PM * SpeedEvil is pondering redoing a strimmer with an upgraded motor.
05:30 PM SpeedEvil: http://www.goodluckbuy.com/hengli-w6025-kv300-brushless-motor-for-rc-quadcopter-hexacopter-multicopters.html or so
06:34 PM divxdude: how the hell can u say audio pitch does not indicate rpm?
06:34 PM divxdude: my variable speed drill says you are wrong
06:35 PM divxdude: it makes an entirely different noise a low speed that at full on.
06:40 PM divxdude: car or bike starters can be an excellent low cost source of 12v horspower if this danger can be mitigated
06:40 PM divxdude: a beefy 12v motor is expensive
06:43 PM divxdude: still need to pack 24v or 36v worht of battery in there also to run the drive wheels
06:53 PM divxdude: current draw does not accurately reflect rpm under varying load condiition. draws more going uphill than down
07:37 PM rue_mohr: "starter": short circuit with an education
07:41 PM divxdude: strict temp based shutdown and or vibration monitoring
07:43 PM rue_mohr: you know that with a dc motor, current is related to torque and voltage is related to rpm
07:44 PM rue_mohr: a starter is a series wound motor, so its not completely linear
07:44 PM Tom_L: so if the cops use pepperspray on perpetrators, doesn't that just make them more seasoned criminals?
07:44 PM rue_mohr: hah
07:53 PM divxdude: the mosfets output can be monitored
07:54 PM divxdude: pulse counter