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DIY Self Driving Cars


  • My 2019 Honda CR-V offers limited self driving via adaptive cruise control and lane assist.
  • The adaptive cruise is good – it controls speed while keeping you a fixed distance from a car in front.
  • Honda’s lane assist is pretty terrible, it’s supposed to keep you within the lane on a motorway.
  • For ~$1k, offer a plug and play dash camera that integrates into 92+ cars and provides much improved lane assist, plus a driver facing safety camera.
  • I bought and installed it. Here’s what I found.

The Basics – Adaptive Cruise and Lane Assist

Most new cars now have some level of self driving. For years, cars – especially automatic drive shaft cars in the US – have had cruise control, which allows you to fix the speed at which you drive. That’s a big help, but annoying if there is a car in front changing speed that forces you to disengage and control speed manually.

Adaptive cruise uses radar to detect objects in front of the car and thereby keeps your car at a fixed distance from the car in front. I’ve driven this feature on my Honda CR-V, but also on a Toyota Corolla, and it works very well. It makes motorway driving a lot less tiring.

Lane Assist is a different kettle of fish. For lane assist, there is a forward facing camera in the car that sees lanes on the road, and keep you within the lanes. Honda Sensing does this on the CR-V, but it really only works well on motorways. Annoyingly, it requires you to touch the steering wheel every 5 or so seconds or else it disengages. Moreover, if there is much bend at all in the road, the system loses track and you have to steer the car manually. In all, the benefit of lane assist is very minor with Honda (or Toyota’s) current capability (this article was written on Jan 1 2021). – the next level

Now comes the DIY approach, which allows you to keep adaptive cruise, improve lane control greatly, plus add some safety features. The solution is a dash camera (the Comma 2), that adds a front facing camera and also a driver facing camera to your car. The Comma 2 also draws from the car’s native front facing camera and radar systems. Lastly, Comma 2 provides input to your car via the OB-II service port under the driver’s steering wheel so that it can control your accelerator, brake and steering wheel.

For regulatory reasons the Comma 2 is not a self driving product. It is “merely” a driver dash cam allowing you to record your journeys. However, by downloading some open source code (Open Pilot), you have the option – entirely at your own risk – of using it to run some pretty sophisticated self driving.

A quick review of the features of (comparing to Honda Sensing as the benchmark):

  1. Adaptive Cruise (adjusting your speed to cars in front) – Comma behaves largely the same as Honda Sensing. At some points Comma is smoother than Honda Sensing in slowing down, at other times it’s the inverse. One slick feature with Comma is that, when your cars slows all the way down behind another car at a stop, Comma will have the car take off again once the car in front moves, whereas Honda requires a prompt by pushing the accelerator.
  2. Lane Keeping – Comma is streets ahead of Honda Sensing on lane keeping. While Honda’s lane keeping frequently shuts off, Comma can take you along street roads – avoiding obstacles – and does very well on motorways. A big advantage for Comma is the driver facing camera – that starts beeping if you look away from the road. This means you can drive for long distances (at least on the motorway) without having your hands on the steering wheel at all.
  3. Safety – I’m repeating myself here a bit, but the driver facing camera adds a layer of safety that isn’t there in Hondas (or in Teslas). George Hotz (founder of Comma) is of the opinion that all cars will need to include a driver facing camera to achieve full self driving safely.

BTW, Lex Fridman’s two podcast with George Hotz of Comma are phenomenal – one and two – the best podcasts I listened to in 2020.

Some worked examples on !

Highway Driving

Here is a video of Comma 2 on motorway driving (not me, someone else on youtube). The one caveat I would give, at least for the Honda CR-V, is that the motorway needs to be quite straight in order for the system not to require you to touch the wheel. It’s not as bad as the Honda Sensing’s native system, which disengages very easily, but Comma Ai does disengage if there is a turn of roughly 20 degrees. I’m not sure if it’s an issue with insufficient steering wheel torque (the self driving system uses power steering to turn the wheel) OR whether the field of vision of cameras is not good enough when there is more bend in the road.

Street Driving in the Honda CR-V with my friend

This video gives a sense of what the car can do on streets from driving with my friend. Note that Open Pilot can definitely not turn around corners, but it can move the car side to side in order to avoid obstacles when driving along a straight street. For most of this video, I have my hands ready to intervene, but I don’t touch the wheel. vs Tesla

I have driven a model 3 once, but I didn’t use much of the self driving. A few key differences, as far as I understand, between Tesla and Comma’s Open Pilot:

  • Tesla self driving costs $7,500, Comma costs $1,200 (including a connecting cable).
  • Tesla – from a regulatory standpoint – is likely a safer bet. As I said above, Comma is technically only selling a dashcam that you can add your own software to.
  • Comma is limited by the cameras and radar that the average new car has. Teslas have many more cameras – and so they can do things like parallel parking automatically, that Comma can’t do for hardware reasons.
  • As I gather from George Hotz of Comma, Tesla is more advanced (Elon Musk reckons they will have fully autonomous driving in 2021), but they obviously have spent tens of billions more than Comma, which has probably only spent a few million to get where they are.

That’s it for this week. Next week will be a technical review of Long-fi systems – long distance wi-fi systems that you can set up in your home, and earn money on for providing the service. You can sign up for my Engineering Business newsletter if you’d like to get an update:

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