AutoBot

Discussions around autonomous, semi-automatic and intelligent robots and systems.

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Lincoln
Posts: 141
Joined: Sun Feb 29, 2004 12:00 am
Location: Olney, Milton keynes

Re: AutoBot

Post by Lincoln » Mon May 14, 2018 3:19 pm

looks pretty good. maybe if i make another antwight scale pcb then ill use that chip but it dose indeed seem difficult to get. but there is a pololu board available with it on.
i would say that the 10V minimum input would mean you have no choice but to use at least 3 cells rather than 2.
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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Lincoln
Posts: 141
Joined: Sun Feb 29, 2004 12:00 am
Location: Olney, Milton keynes

Re: AutoBot

Post by Lincoln » Sat Jun 02, 2018 11:38 am

note to self. when probing the motor driver pins, be EXTREMELY careful.

all was going well, we were testing the new motor driving algorithm on the driveway, then we decided to put it in the grass, it doesn't move, seems the motor gearing is to low to have enough power to go though grass. which means getting new gearboxes. but this test also burnt out one of the motors so we have to replace than as well. then we notice that one of the motors would work off of a power supply but not off the motor driver. so we were probing around it, decided that the mosfet that powers it was maybe dead so replaced it no issues. but the motor still wouldn't turn. continue probing the pins.
OH now the processor has stopped, and isn't programming. ah whys it pulling an amp and is boiling hot.
turns out that a signal wire to the processor (3v) and the charge pump (15v)for the mosfet are right next to each other! so we must have shorted these two pins together when probing around. it turns out processors don't like 15v.

expensive day of testing that was. need a new processor, probably a new motor driver, a new motor, and 4 new gearboxes.
Team RobotMad, home of the Smart robots, and very mean pots :)
Chris and Lincoln Barnes

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MarkR
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Joined: Mon Dec 18, 2017 12:46 pm
Location: Reading Hackspace
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Re: AutoBot

Post by MarkR » Sat Jun 02, 2018 8:35 pm

Unlucky.

Something probably a bit less technical but similar happened to my Raspberry Pi antweight. It seems that the Raspberry Pi Zero W does not like 18v on its 5v input, it made it rather unhappy. I don't know yet whether the sd card survived, I hope so.
Robot: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?

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Lincoln
Posts: 141
Joined: Sun Feb 29, 2004 12:00 am
Location: Olney, Milton keynes

Re: AutoBot

Post by Lincoln » Tue Jul 17, 2018 5:53 pm

right, we finally put some time into fixing PlankBot the AutoBot prototype and designing AutoBot.
new cpu on the board done all working, new motor driver chip, massive pain to solder because of the large pads on the bottom that mean we have to hot air solder it. which when only doing one chip in a row of 4 means they all move and basically is just a massive pain, then just when its done the stuff falls off the other side of the board because hot air soldering is such a joy.
so eventually that was fixed.
we bough a cheep Chinese version of the motors we were using before with 47:1 gearboxes instead of 9.7:1.
ordered all the parts for the new AutoBot.
lots of 15 mm square extrusion aluminium called OpenBeam, some 3 mm steal bar, some ball bearings. also got some 1/8th scale nitro car shocks from Ebay for suspension.
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