[Maurizio] built a robot arm, which is always a great accomplishment. But his project includes a very cool touch interface for an Android device that sets it apart from many other similar projects.You can see a very fast summary of the construction in the video below.
The design uses Fusion 360 and there are good explanations of each step in the process. The gripper is adapted from an existing design. Various 3D printed parts make up the wrist, shoulder, elbow, and rotating base.
Electronics-wise there is an Arduino, 6 RC servo motors, and a Bluetooth module. Inside the controller is mounted an old Android phone. Honestly, we are always surprised we don’t see more of this. We all have old phones hanging around and with constant power connection and running dedicated software, they make great free touchscreens for projects.
The Android code is very simple thanks to the Scratch-like App Inventor software which makes Android apps as easy as dragging some blocks around. You can download the APK but you have to ask for the source code for the app since the project hosting site wouldn’t take it — maybe he’ll mirror it on Hackaday.io.
We are always surprised we don’t see more App Inventor projects, although do see some. If you want an easy introduction, you might think about this project.
With no position feedback to main controller this is just an expensive paperweight. It’s not only about being able to reach some coordinates, there are also different motion interpolation algorithms and probably lots of other interesting stuff that can’t be done with RC servos.
Cheap closed loop stepper motors have caught my eye on Aliexpress recently, not sure if they are new to market, or just new to me, but they look intriguing.
You can modify them to add positional feedback, or you can add encoders or similar to get feedback.
That old phone could be utilized a bit more. The camera on it could be used for the end effectors positional feedback. just put a couple fiducial markers on it. Not to mention if it has a good IMU, gyro, compass combination, but then you’d have to live with your interface being on the end effector itself.
I like it, though. A very good intro to robotics control.
Hi, I’m Maurizio. Thank you for posting it, love you guys ❤️