Learn the Math behind Odometry | Essence of Robot Odometry Pt. 2

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Күн бұрын

How does the math behind odometry all work out? How do robots know where they're facing? An in depth explanation of the robot odometry tracking theory used in VEX and FRC robots.
Check out the next video of the series on the Math behind Position Odometry: • How do robots know whe...
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Full Odometry Playlist ⏯: • Essence of Robot Odometry
Check out the previous video here⏯: • What is Odometry? | An...
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Timeline:
(0:00) - Introduction
(1:36) - Placement of Tracking Wheels
(4:06) - Arc Tracking Theory
(5:35) - Calculating the Arc Angle (Orientation of the bot)
(9:17) - Outro
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For those who want to learn more, I highly recommend this document by Team 5225A introducing their position tracking system, which helped play a major role in them becoming the 2018 Vex World Tournament and Skills Champions: thepilons.ca/wp-content/upload...
Team 5225A has also graciously released their winning code as an educational resource here: github.com/nickmertin/5225A-2...
I also highly recommend this other paper by MIT on odometry and motor controls: bit.ly/3duutTw
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#Odometry #Robotics #ControlTheory #VEX #FRC

Пікірлер: 35

@RexLiu 2 жыл бұрын

Hey everyone, sorry for keeping you all waiting. Part 3 is out now: kzfaq.info/get/bejne/p9d_d6yV27mrkZc.html. Enjoy!

@everythingeverythingcardbo2658 Ай бұрын

You are so good at teaching! Everything was understandable and incredibly helpful!

@JaafarElousami Ай бұрын

You are the best

@notjjdj3992 3 жыл бұрын

Incredible video, keep up the good work man!

@RexLiu 3 жыл бұрын

Thank you! I'm glad you enjoyed it.

@kendallsteele8061 2 жыл бұрын

WE NEED PART 4!!! Pls

@sebbe95m 2 жыл бұрын

Amazing job with teaching !

@RexLiu 2 жыл бұрын

Thanks for the kind words!

@elijared1162 2 жыл бұрын

thank you for making this! as a member of an FTC team, it’s so hard to find resources for more advanced coding help

@RexLiu 2 жыл бұрын

I'm glad it helped. Good luck this season!

@ohrange5380 2 жыл бұрын

Awesome bro... I loved the way you explained it...

@RexLiu 2 жыл бұрын

Thanks, more videos to come!

@burrito1474 2 жыл бұрын

keep up the work

@RexLiu 2 жыл бұрын

haha, will keep that in mind

@jacobkrebs4342 2 жыл бұрын

Love the video. Part 3?

@RexLiu 2 жыл бұрын

Part 3 is out now! kzfaq.info/get/bejne/p9d_d6yV27mrkZc.html

@randylujano666 2 жыл бұрын

Great Vid! Part 3?

@RexLiu 2 жыл бұрын

Thanks! Part 3 is out now! kzfaq.info/get/bejne/p9d_d6yV27mrkZc.html

@xTigr 2 жыл бұрын

Does the placement of the tracking wheels change where the tracking center is? Or is it always at the center of rotation of the robot?

@braydensmith6069 Жыл бұрын

For the distant from the tracking wheel to center point is it the center of the wheel or the closest edge of the wheel?

@cucubob9535 Жыл бұрын

hey man, when is part 4 coming out, I see ur responding to people here so I thought I could ask to see if I could get a response

@pronpalunpo1066 Жыл бұрын

what if delta s is outside the circle and delta left and delta right are on the circle? do we have to calculate this case ourselves?

@rogueroboticsinc 3 жыл бұрын

Amazing video! when will the next video be out?

@RexLiu 2 жыл бұрын

Next video is out now! kzfaq.info/get/bejne/p9d_d6yV27mrkZc.html

@lucaszhang8226 Жыл бұрын

is the delta left and right just the distance that those tracking wheels had traveled?

@stardust5175 2 жыл бұрын

Wait, my team is making a a tank drive and we are trying to figure out the placement, but we plan on only using 2 odometry wheels, like a differential bot. So our odometry wheels have to be on the midline right?

@RexLiu 2 жыл бұрын

Hi, if your team plans to use only 2 odometry wheels that are parallel to each other, you would only be able to calculate the orientation vector. Without a perpendicular tracking wheel, you lose out on the ability to calculate the position vector (x and y coordinates). I go into more depth on how that's done in Part 3 of the video here: kzfaq.info/get/bejne/p9d_d6yV27mrkZc.html. If your team is unable to use 3 tracking wheels, my recommendation for a 2 tracking wheel system is to position them perpendicular to each other, this way you can still calculate the position vector, albeit you lose out on orientation. To find the missing orientation, the inertial sensor is a great choice that takes up less space while providing data with similar accuracy. As for placement, if you go with the first option, your tracking wheels do not have to be on the midline as long as they follow the 3 rules outlined here: (3:12). That is, they must be parallel to each other and perpendicular to the tracking center. Hope that helped, let me know if you have any more questions.

@angrybokoblin8777 2 жыл бұрын

When coding odometry for an x drive, how does an arc approximation work? An x drive almost never moves in arcs. Wouldn't adding vectors each cycle be a more accurate solution?

@Zach929U 2 жыл бұрын

While it looks like the robot is driving in a straight line it is realistically impossible that it would be from imperfect hardware and electronics. Therefore, we can assume the robot is driving on an arc of a circle with a very large radius and the calculations still stand very accurate. Since we are measuring these distances over very small time intervals you can imagine that circles even with radii of 6' could have a segment that satisfies the measurements we just recorded from the tracking wheels. If none of this is making sense you could also just open an image of a circle and zoom in really far on the outline to see eventually it appears as a straight line but in reality is an arc segment. Hope this helps.

@angrybokoblin8777 2 жыл бұрын

@@Zach929U yeah that makes sense, just was wondering because the x drive moves so fundamentally differently than a tank drive and the code looks tailored to a tank drive.

@aeku_69420 2 жыл бұрын

@@angrybokoblin8777 In case you still are curious, a straight line is just an arc with infinite radius.