Description

D-Ov2Evo is an evolution of Michael Baddeley's awesome D-Ov2 design. It takes what makes D-Ov2 great:

• Eccentric Lazy Susan type printed drive wheels
• Rigid body-to-neck and neck-to-head linkage with direct servo coupling
• Lightweight head linkage and structure

...and improves it by adding:

• Fully software-controlled Dynamixel servo setup
• Encoder motors and modern IMU for smooth and reliable drive control
• Quick-change battery trays with 18650 batteries
• Standardized electronics
• Fully parametrizable software with serial and WiFi command-line consoles and parameter storage.

D-Ov2Evo is Not A Beginner Project.

WE MEAN IT.

D-O is small and cute but is not an easy build by any means, although we're trying to make it a lot easier. You need at least:

• (A friend with) A well calibrated printer capable of printing at least PLA+, PETG, and TPU, although a printer with an enclosure is very recommended so you can print ABS or ASA.
• Some soldering skills. Our electronics come pre-soldered with the SMD parts but you will need to solder some through hole components. Issues caused by bad solder connections are very hard to debug remotely. Adafruit has an excellent soldering tutorial.
• Basic skills with a multimeter, for checking connections ("buzzing through") and measuring voltages, resistance and currents.
• Some skills in flashing and testing Arduino code (BTW we use PlatformIO for most of our development).
• A lot of patience and frustration tolerance testing and tuning your droid. The path is hard but the reward is great.

The reason why we write the above is that this is a project run by two people, who both have demanding long hour day jobs and sometimes like to tinker on non-D-O things. Remotely tracking down and support issues that stem from lack the required skills mentioned above is taking up time that we then cannot invest to help tune your droid's motion parameters to make it look just right. So please do yourself a favor and only tackle this project if you are confident about your proficiency in the above skills.

Print Files

After subscribing to Michael Baddeley's Patreon (with the intermediate tier at least), you will have access to the EarlyBird folder. It contains a directory called D-Ov2 in which you will find all the original print files.

Our changes to D-Ov2 can be found here: https://github.com/bjoerngiesler/D-Ov2Evo-STL We have Michael's express permission to post these files on GitHub as long as they do not contain the full model, and GitHub will allow better versioning as parts change and improvements are submitted. (If you have a change to a part you want to submit, please create and submit a pull request!)

The contents of that GitHub are structured with the same folder structure as the original print file folder, and each subfolder contains an instructions document specifying which files to take from the original print files, which ones from the D-Ov2Evo files, how to orient them, printing materials etc.

BOM

...is here. Please let us know if you find that parts are discontinued and/or think we should use an alternative better part for anything.

Documentation Collection

The build documentation is spread over basically three sources:

• Your first source of info should be the instructions files on the individual component groups in the print files folder. They tell you what files to print, what materials and settings to print them in, and also contain the hardware required to assemble the individual component group.
• There is a video tutorial series over on YouTube that accompanies the build process, talks about electronics, controller tuning, etc. etc.
• This Wiki page is intended as a reference, for background info, drawings, connections etc. If you're hung up on a detail please refer to here.
• Contact options:
  • If you have any questions, post in the discussion list here on Github or contact us on Facebook or Instagram.
  • If you think you've found a bug or want to request a feature in the software (but only there) submit an issue.
  • If all else fails, feel free to drop us a line under [email protected].
  • Please remember we are two dudes doing this in our rare spare time, so please cut us a bit of slack in your expectation reply frequency and jitter. :-)

Battery Safety

D-Ov2Evo uses quad 18650 batteries, in two 2-battery packs, for power. These are LiIon batteries with high energy density, but not LiPos. The battery packs do not include battery savers or hardware-level undervoltage or overcurrent protection, but the system hardware and software do.

1. The power board has an INA219 voltage / current sensor and the software will switch drive motors off, and a bit later servo torque, if voltage drops lower than 3.2V/cell. At the same time the droid will start blaring "voltage too low". The battery status also gets reported to the remotes.
2. 18650 cells are safe until a voltage of 2.5V, or 10V. This depends on the cell but is the max of mins that we have seen; some cells can be discharged to 1V per cell and still be charged. The Arduino shuts off / starts brown-outing at 12V, or 2V above the worst case min voltage of the battery cells.
3. Overcurrent protection is handled by the fuse holder on the Power Distribution board.