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Topic: Balancing Robot Troubles (Read 1 time) previous topic - next topic

Abhishek_G

#15
Apr 04, 2016, 04:16 pm Last Edit: Apr 04, 2016, 04:33 pm by Abhishek_G
Hi Abhi, your original bot was certainly zippy enough. I believe that your original bot was certainly capable of balancing really well. I don't just mean trying to balance..... but actually balancing extremely well. I believe it's just a matter of working on the software (control algorithm), plus PID settings, and making sure the sensors are giving decent/clean readings.

Steppers tend to draw a lot of current when the motors aren't turning much, and will likely drain battery quickly. Will still be interesting to see the results from the stepper motors though.
Hi Southpark,
Agreed, the bot was zippy enough. but it couldn't hold its position(gear backlash) and also, as the gear ratios were high reduction, the final speed was low. So I decided to use a couple of steppers. I know, steppers will draw a lot of current, but at the moment I'm powering the bot with a laptop adapter.

That said, I have completed building the new bot(new bigger frame, new drivers, motors, bigger wheels). And glad to say, the newer bot runs amazingly! It holds position like there's no tomorrow.

I've used a couple of Pololu DRV8825 drivers to run two MotionKing NEMA17 steppers(1.3A per phase, 4-wire, bipolar) and the AccelStepper library  (http://www.airspayce.com/mikem/arduino/AccelStepper/index.html) for controlling the motors.
The bot holds position wonderfully, like I said earlier. But the only issue I have is with motor speed. The UNO can give the steppers a max speed of 4000 steps/s due to its clock speed limiting the pulses. I'd require a Due now, for its higher clock speed(84MHz).

Apart from that, there's absolutely ZERO problems in the balancing part. :D
Now, I'm working on adding a couple of ultrasound sensors, to make it a basic obstacle avoider or follower.


Here's the video of the bot in action: https://www.youtube.com/watch?v=cobwLFzAhv4

P. S. - Sorry for the delayed response, working on the new motor drivers took away a lot of time.

Southpark

Hi abhi. Your bot is balancing excellently. I knew you'd get there. Congrats in getting it nice and stable. Looks great.

Abhishek_G

Hi abhi. Your bot is balancing excellently. I knew you'd get there. Congrats in getting it nice and stable. Looks great.
Thanks!
That's very kind:)
I'm working on the "follower" part, which should be completed by today(its 10.24am here). Will keep the thread updated and will soon post the video.

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