Openpilot has come a long way

My trusty old 2003 bmw 540i wagon has served me well for years, while constantly breaking down and sucking down premium gas at 16mpg.

One day it’ll be electric, but in the meantime, i need to be able to commute through the bay area’s famously bad traffic without losing my marbles.

It turns out, an entire community has sprung up around taking Openpilot, an open source autonomous driving stack, and modding older cars to be controllable by it.

Picking up the torch

Turns out someone else beat me to this problem, but never fully executed on it

https://github.com/killinen/BrakeModule

That someone else came up with a clever solution to control the brakes on this old car, which doesn’t have brake by wire…..by gently actuating the ABS pump without the car even being aware. A true man-in-the-middle attack, with an arduino and some cheap relays

The plan is to pick up exactly where this person left off, and improve on what he initially laid out

The problem with old code

Unfortunately since he made that code and that module, openpilot’s hardware stack as evolved immensely, The latest one (as of this writing) being the Comma 3x, a $1000 all in one unit that’s far more capable, but luckily a lot of principles will carry over

The trick is to lie to the comma 3x, and say it’s connected to a totoya corolla from 2017, which has extremely simple protocols and canbus commands that are easy to replicate in simple arduino code.

However, even then, this code was designed for several major openpilot releases in the past, so the interface itself will likely need to be rewritten from scratch

But that’s fine, he did most of the needed discovery, I’m just coming along to modernize it

The shopping list (on a budget)

Turns out buying the comma 3x isn’t even needed to get all the bugs out, Openpilot runs just fine within WSL2, which is a sort of linux bedrock / simulator which Windows can run on. More importantly, this can all be done for $free instead of $1000

That said, there’s still some costs involved

The throttle pedal needs have its signal “intercepted”, so the human can still use the throttle, but openpilot can also manipulate the throttle when its in control. To that end, a very simple sedup with an arduino nano, a canbus transceiver is all you need.

The Nano acts as both a DAC (digital to Analog converter) and ADC (analog to digital converter) at the same time.

The throttle pedal has two potentiometers in it, which receive a stable 5v reference signal

The general diagram is the arduino and can transceiver sitting right next to the pedal, constantly either relaying pedal position uninterrupted when open pilot isnt running, or acting as a “fake” throttle pedal, listening to OP’s commands

• parts for the brake controller

Driving the bench

• sim racing wheel
• canbus sniffing

Future stuff

• Radar module
• Steering control