ODrive Discussion 6/11/22

[qhdwight]

• Can use SocketCAN on the Jetson to communicate with the ODrives instead of going through an STM chip
• Embed safety features and error checking from day one, don't patch it on later
  https://docs.odriverobotics.com/v/latest/can-guide.html
  https://docs.kernel.org/networking/can.html#how-to-use-socketcan
  Old proposal: https://docs.google.com/document/d/1szt_H__a7p0-Q6rNIuwunpLf8Qpiobd_QL9ndcWEWMg/edit

[qhdwight]

1. Buy CAN transceivers in bulk. Connect one between the Jetson RX and TX and the main CAN network
2. Set up a test bench with Jetson Xavier, ODrive, and Salae
3. See if you can use SocketCAN in the catkin workspace to make a motor spin

[tabiosg]

Ok as a follow up, I was planning on migrating the drive code to use CAN but there is one pretty big issue: The watchdog functions that we use are NOT supported in CAN for the ODrives. This includes the enable_watchdog, disable_watchdog, and watchdog_feed functions. I'm pretty sure we do need these functions for when we switch between disconnected and armed states. @sashreek1 and I should first test to see if we can do without these functions, but if we can't, then switching over to CAN for ODrives may not be possible.

[qhdwight]

I can't imagine something similar is not supported. According to this it is something you set as config? And you send CAN commands to feed it according to this:

The watchdog is fed using the axis.watchdog_feed() method of each axis. Some ascii commands and most CANSimple commands feed the watchdog automatically.

[tabiosg]

So I'll be able to feed the watchdog without any problems (that's easily done with CAN). The problem is that they don't have the command for config.enable_watchdog and config.disable_watchdog since it can not be found here.

I do think that it's sus that we've been changing the config parameter in our program but I'm pretty sure we implemented as a way to find our way through errors of losing connections to ODrives and having to modify those parameters to reset the watchdog. Either way, I'll have to test.

[qhdwight]

I thought these configs were done via the Python odrivetool? And then they persist.

[tabiosg]

yea so basically configs persist but in our code we actively change it