For my capstone project at Northeastern University my team is working on a telepresence robotic system that utilises an exoskeleton strapped to a real person’s arm and a robotic arm that mirrors the user’s movements and provides haptic feedback. We want to use ODrive motor controllers because we like the open source nature and their reputation as a good option for hobby projects similar to ours.
However, we have to make our own custom PCB with a smaller footprint than the standard ODrive board because it’s imperative for our project that we can place it on the arm/exoskeleton as close to the encoders as possible to minimize noise on the SPI lines.
We still plan to use ODdrive firmware, and our PCB will be based on the ODrive hardware using the schematics that are publicly available. The official hardware schematics have not been released for the latest version (v3.6) and we are not sure if the older versions we would use as reference (3.4 or 3.5) support all of the functionalities that the latest firmware version offers (v0.5.1). In particular, we need support for absolute encoders over SPI to use with out AS5047P encoders. Do hardware versions 3.4 or 3.5 support this feature? If not, is there a way to modify them to support it?
I would use differential signalling for off-board SPI instead, or wait for ODrive 4.x.
3.5 schematic is very similar to 3.6. Also, I will reach out to Oskar to see if we can get you some beta boards of 4.x, since you’re an educational customer. No guarantees though
Thank you for the advice, sorry for the delayed response. We are currently working on setting up differential signaling for the off board SPI. The team would be thrilled to work with a version 4 board.
Our team is currently analyzing several different options for single axis motor control with an absolute encoder. We will produce a report analyzing our finds at the end of our project, which we would be happy to share with you. The ODrive is a promising device for haptic control, we look forward to hearing back from you soon!
Please sign up to the v4 beta here. Our timeline is pretty uncertain at the moment, all I can say is it will be some time in 2021.
I agree with Wetmelon, the easiest way forward is to use standard ODrive v3.6 and sheilded cables for the encoders, or even differential. Though for the latter you will need an addon board for the ODrive. I know Wetmelon is working on a design for that. @Wetmelon Do you know what the timeline of that might be?