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Animatronic Tail (ESP32)

PearlFish

Oct 18, 2023
2
Joined
Oct 18, 2023
Messages
2
Hi all, first post here :D
So I would like to make an animatronic tail for use at festivals/fancy dress etc. I have a pretty good idea of what I want & think I have a rough idea on what I need to do, So I guess this initial post is asking for people to double check my work to see if I am heading in the right direction.
I am not asking for anybody to do my work for me as I find half of the fun with these projects is working out how to do it. I have been using Arduino's for various toy projects over the past 4-5 years but have never used an ESP32 before. I am also very confident with 3d design & printing (plus supporting craft skills).
Also, I really was not to sure where to post this as I find it hard to classify what category it should go into but as I have a pretty good concept as to the hardware & 3d design side of the project, this is mostly just going to be discussing the programming of the ESP32 so thought this would be the best place. Apologies if it is not & would appreciate being pointed in the correct direction.

So, onto the planning stage!

Basic concept -
Approx 60cm long tail on a flexible spine, 2 control strings running the length through vertebrae separators attached to 2 servo mounted pully's. This is where I should have added a render / image of the arrangements to make it easier to visualise, will work on that tonight & edit this post! But try to imagine an end on view of a vertebrae with an upside-down triangular arrangement of holes, the spine passes through the lower hole the entire length of the tail, the 2 upper holes are where the control strings pass through...... pull the left string - tail deflects to the left, the right string - deflects right, pull both & the tail lifts up. I hope that description kind of makes sense.

Project goals / constraints -
1 - Electronics only need to be slightly shower proof as I do not intend to wear it during rain. Final design will be fur covered so thinking that getting it water soaked will add far to much weight for the servo's & even just to wear. As long as it can survive an emergency run (powered off) to the tent/dry storage should it start raining then all will be fine.
2 - Interchangeable batteries as I will not be near a charging point while at a festival for 3-4 days hence why I was thinking 18650's as they are small/lightweight & I can pre-charge extra's to take.
3 - Wireless control for pre-programmed motion - This is one of 2 reasons I am planning on using an ESP32 (other reason is planning another festival/costume project later down the line which will require face tracking from an ESP32-Cam, so this will be a relatively "simple" project to get started with).
4 - MPU6050 for motion detection while walking to give a natural sway to the tail.
5 - Be as self contained as possible so I can design a quick release for a belt mount as I will be unable to sit down while wearing it. Worst case scenario would be a belt mounted battery pack with a wire/jack plug to the tail.
6 - Trying to stick to a reasonable budget, after all I'll still need to spend out on costume & festival tickets lol

Initial circuit concept -
Please ignore how quickly I put this together in photoshop as its more of a parts list / consideration brainstorm thingy but I think it should make sense. Obviously if people think this might work then I will go through & make a finalised circuit design with correct pins etc.
The circle with the "???" is because the voltage will be 7.2v & I am aware that ESP32 is 3.3v. I have read that some of the NodeMCU boards have a voltage regulator on the "VIN" pin, so not sure if I need to add an external regulator?
Also I forgot to add a power switch to the positive coming from the battery pack but I am aware I need one!

tail electronics.jpg

Finally the very basic concept for the programming side of it -

I know that using the BLE side of things would be the preferable wireless interface but that would then add the addition of needing to learn how to write a bluetooth client for IOS, so thinking that I would be better working on a simple wifi webpage initially & just connect when needed. At the very minimum I just need to have a set of "mode select" buttons, but maybe later on adding some extra controls so I can tweak movements on the fly or perhaps get motion/battery voltage information etc.

Modes -
1 - Idle - random small flicks / motions of the tail while there is little to no movement detected from the MPU6050 - Listen for movement change / web commands.
2 - Motion - movement/sway depending on detected motion from MPU6050 (no motion detected, return to idle) - initially will be simple sway left/right to balance walking & lift/drop when leaning forward/back. Depending on how this works out, may add acceleration variables later on.
3 - Pre-set mood "animations" - I guess this would be a collection of different servo position loops like you would see a animatronic play through. the idea being that there would be 4-5 different animations for each "mood" so if you press the "happy mood" button it will select a random "happy" animation to play before returning to "idle"

Outro!

If you have read this far then thank you very much for taking the time :) As I said before, I do not want anyone to do my work for me as I am looking forward to the experimenting & learning side of the project, this post was really just so I could outline my plans & idea's for the project to see if it is feasible & that I am thinking about it the right way, I don't really want to spends loads of time & monies working on this if one of you peeps can spot an issue before I even start!
As it stands right now, I have all parts other than the ESP32 & the central spine cable for the tail. I am currently working on the design for the tail sections which I am hoping to have printed by this time next week (away this weekend & need to wait for delivery of the spine cable) which will then give me chance to manually test the physical movements by hand before designing the housing for servo's/electronics.

Thank you in advance & I look forward to sharing this journey with you all :D
 

PearlFish

Oct 18, 2023
2
Joined
Oct 18, 2023
Messages
2
Thank you for the reply @Delta Prime. That is pretty much the exact system I use at the moment, nice & cheap, good battery life, easy to do.
However my plan is for something like the "MiTail" or "CosTail" as they have so much more "emotion" to their movements & also by doing it myself it will make it easier to hook into other future projects I have running through my mind. As stated before I am not posting here so much about the mechanical hardware side of things as I have a pretty good plan which will probably look a little more obvious with the attached photos. This is more so about the programming side of an ESP32 or suggestions on what might make for a better microcontroller for the motions I am trying to achieve.

So this is basically just an animatronic tentacle based design as there are plenty of information about them online/youtube etc. I know there are 3d print files others have made, but it defeats the project goal of learning new things if I just download & copy which is why I am trying to design my own while taking inspiration from the others.

Side note before I post images..... while writing this I have also considered that programming may be easier if I add a third servo dedicated to the "lifting" of the tail. Initially I did not want to do this as keeping the mechanical/electronics box as small as possible was another goal I had not mentioned, but will have a play with the design tomorrow to see how much extra size that would add. I am thinking that leaving the left/right servo's dedicated to swaying movement would be much easier than trying to make animations where they also have to offset for the "lift" movement, having a dedicated "lift" servo would no doubt save headaches!

So here are 3 photos showing deflect left/right and lift. I hope they make sense :)


tail 01 left.jpgtail 02 right.jpgtail 03 up.jpg
 

Delta Prime

Jul 29, 2020
1,970
Joined
Jul 29, 2020
Messages
1,970
Sorry about that buddy.
I stopped reading after the first sentence.
Someone will be a long shortly to help you.
 
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