< We need to talk type of situation >
This is a short update about the lower part of the assembly.
The Gist (Maybe)
So I came back from the bar after fumbling another American. 7 boxes of JLC PCB later, we have a lot of things to discuss.
The robot hand part of this project is nearly complete, with the arrival of all the 3D printed components, the mechanical part of the project is complete. The assembly of the electronics is also nearly finished with some wires still remaining to be connected.
AND YES AGAIN, all the label text on the PCB are in HINDI and FRENCH because I made it. Just a reminder.
The project uses ROS2 and a micro agent of ROS on all the ESP32 micro controllers which are connected wirelessly(via WIFI) to the host PC.
Next up to train my models, I will be using google mediapipe and its resources.
I use a combination of python and C++ to run the main ROS system on the host PC. Python mainly for google and its resources. C++ for intercommunication with the micro controllers and debugging. ROS seamlessly takes care of it.
The electronics is simple, 23 individual switchable power regulators for each servo, 2 PCA9685 multiplexers connected to 2 ESP32 micro controllers. That's it. One of the ESP32 handles all the ROS communication via WIFI and sends the info to the other via UART to the other ESP32 for all the I2C connected devices to the second one.
Here's a little video for the robot palm's size reference to mine (it's 1:1) - Youtube
In the first picture, the complete model of the palm is shown. YES that guy in the reflection is the GENIUS behind it.
The pulley system with the finger tendon and nerves is on the way at the moment.
The Lower Assembly
First off, we start with a 3D model.
In the model, it should be obvious it uses a LOT OF SERVOS. A price for salvation: use all the servos the world has to offer. In this case, I actually bought the last 20 the seller had—a close call. 5 are for backup.
So, the whole hand consists of just 3 sub-assemblies: the palm, the wrist, and the lower assembly.
Today, we are focusing on the third one. T.L.A (The Lower Assembly) is basically composed of 3 main printed parts: the servo case, the circuit case, and the universal connector.
The servo case holds 15 servos with a pulley and a block to route the strings. The circuit holder carries two circuits, which will not be mentioned because I’m too lazy.
The universal connector is a two part design so basically the connector hooks to the hand and the various nut embedded holes allow for another connector to be connected for it to be attahced to any arm present on the market. The second connector in qustion could be deisgned by anyone in a few minutes and take an average of 15 - 40 euros to manufacture. It's meant to be cheap.
Besides this, the whole mechanism was made to be straightforward as there were a lot of cables, around 35 to be connected in different places.
Pretty much that’s all. Very simple sub-assembly. HAS A LOT OF BOLTS. BECAUSE I MADE IT.
If you have a good designer’s eye, you must have noticed those elongated holes instead of regular ones. These are for alignment during assembly along the X-axis, due to the questionable quality and dimensioning of some parts. Why questionable? Because not all the parts are from the same printer, and during assembly, the parts were found to be under tension at two points between the lower assembly's universal connector and the wrist link (which is not shown here).
You can play with the 3D interactive model below to get some insight into how the different parts are hooked together. The circuits and wires are omitted because they take so long to implement in a model. Not doing it. If you want, do it for me.
The Interactive 3D System Assembly Without Circuits
Update, You are Lucky
April, 2025: I made it finally. Here you the fully assembled version with all the electronics. The whole thing was not a piece of cake. I need cake now.
This assembly here features the complete electronics involved in the lower part of the hand. I detailed it as much as possible.
The Interactive 3D System Assembly With Circuits
Bye Bye
P.S Don't hesitate to send me a message or an email if ever you have any questions about this project.
The next post will take a while, until then stay hydrated. drink some bee... I mean water.
good robots, good life
- Made in A.U.T. Room 1552, New Zealand by RolandThsive
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