repurpose automotive radar for UAV/UGV


I was interested in trying an automotive radar for collision avoidance on a UGV. Automotive radar should be cheaper than LIDAR due to scale production and no moving parts, and requires less brains than stereo vision.

I got a Bosch sensor for an Audi Q5 (Audi part 8R0907561) off eBay. The magical search term was "Adaptive Cruise Control". There are other radars from other companies, I got that one because it was the cheapest and there was some information about it on the net.

Hooked it up to my laptop using a CAN-USB interface (photo below). It outputs a steady stream of messages, unfortunately those messages don't change when I change the distance to objects in front of the sensor. An example of the stream of packets is attached. I feel there may be some configuration that is sent to the sensor to get it to output range information. It gets a little warm to touch and draws around 180mA@12V, so something is happening.

What would really help is a log of the CAN bus traffic from an operational sensor. I could replay this log back into my sensor and see if it came alive.

* Has anyone tried to use an automotive radar?

* Does anyone have an Audi with adaptive cruise control and could log some data for me?

PS for anyone who is interested, here is some links about Bosch automotive radar:

Nice summary article talking about Bosch's radar development, no details. I think I have LRR2, not LRR3.

A university thesis about how well the radar detects different objects. Has some details about the CAN messages but none of the messages match what I get. Probably the audi part has a different firmware.

Service manual for Adaptive cruise control in an audi a8 (in German) has some CAN bus and state diagrams.

Some more Bosch marketing material with nice detail (shows LRR3 has much wider field of view than LRR2).

Retrofit of ACC to an Audi Q7, this is where I got the pinout from.

The CAN bus log is from a Kvaser leaf using Kvaser's canlib library, data format is
id length messages[0..7] flags time
- time is in milliseconds
- the logs are taken from start up, so step 1 start logging, step 2 turn on sensor.

script shows the unique messages.




You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –


  • how about this, CAN BUS info about LRR3, not validated














  • Hello guys,

    I'm also interested in communication with such device. I've made some search on the internet and found this article which is google translation of the original russian article They say the radar communicates by SAE J1939 standard, documentation is paid and expansive, but they are got it working after some research. Radar wants some input about speed of the vehicle and direction. The most important key to lunch the radar is to send to it the respond from other ECU, and what is interesting, the content is not important. Important the presence of this message. You can see the messages required to start the device on the picture below: 


    I've bought the Contintental ARS4 radar for extremely low price and waiting for delivery. Hope I will be able to connect it. 


  • Hi Zach,

    I also bought the same sensor (Bosch 8R0907561). I plug it in and see the same CAN messages with the same ID address. Some of these are permanent, some come with brute force from 0 to F, the sensor is clearly tries to register in the system, but that it needs to answer is not clear. Reviewed bunch of articles and did not find the protocol that you need to pass the sensor and how to decode his responses. I would like to know whether you have got to get results and get information about objects seen by the sensor? which protocol uses a sensor? (I apologize in advance for my English - automatic translation Google)

    • Hi Gubenko,

      No I didn't make progress and haven't worked on this for a long time. To reverse engineer the protocol a recording of the messages from a working vehicle is required.

  • Hello all,

    Im going to first start off by saying this is my first time ever posting on any forum. Ive read through several forums, just never been interested enough to actually post. While i work as an Audi Technician at a dealer, i have higher aspirations of becoming an engineer developing software for Advanced Drivers Assistance Systems, much like James M. Point being, this discussion interests me a lot! I also see that this post have been on going for a few years and my not be relevant to some but i hope i can provide input given a have exposure to these vehicles and systems on a daily basis.

    As a technician, we normally dont get as in depth as to read CAN logs. More simply, just evaluate whether the vehicle has a proper CAN signal using a DSO. As some can imagine, from a technician standpoint, that is really all that is necessary to diagnose an issue with a network/control module. But, as mentioned before, i have higher aspirations so I'm not satisfied with just looking at things from a technicians perspective.

    One potential issue i see here is that, depending on the year Q5 the radar sensor was pulled from, it may use Flexray communication, not CAN... Given the original post was 2012, its possible. Earlier models with adaptive cruise used for CAN communication but in 2011 they switched to Flexray starting in the A8. Flexray is supposed to be faster, more reliable, easier to diagnose and also uses a twisted wire pair. Ill have to verify and check to see what year the Q5 switched to flexray and i reference the part number to see if i can get a year range to narrow down what model year the sensor came from, unless you already know. Judging by the way the sensor housing, it looks like a newer style. But i will have to look into it. I can tell you for sure the radar sensor somphong is using is, with out a doubt, a flexray based sensor and the type i typically see.

    I would normally be able to look it up from home but for some reason the audi repair manual website, ElsaPro, doesnt want to display on my browser anymore (maybe a firefox compatibility issue???...) so ill get back with that info. I also have access to the English version of the A8 adaptive cruise SSP mentioned above (service manual). Also, the updated SSP for the newer flexray adaptive cruise systems.

    If it is a flexray system the system consists of 2 radar sensors, a slave and a master along with other modules. The adaptive cruise system also incorporates data from the lane detection camera (mounted in the windshield near rearview mirror) and side assist ultrasonic sensors (in front and rear bumpers) which operate on a high speed CAN network. Communication between the two different bus systems take place through the Gateway Diagnostic Interface Module which can be considered the network communication master.

    When you connect to the diagnostic port of an audi vehicle you dont actually communicate with each control module directly, you communicate with the gateway which is communicating with the modules on various networks. CAN, LIN, MOST and Flexray. There are also different CAN networks too, such as: Drivetrain CAN, Convenience CAN, Comfort CAN, Extended CAN, Discrete CAN, just to name a few. There are also high and low speed CAN (not to be confused with CAN high and CAN low) referring to the data transfer speeds. When two control module on different networks need to share data they communicate through the gateway. In some cases control modules communicate on more than one network, ex. ABS module communicates on Flexray and Powertrain CAN (very dependent on year and model).

    If anyone is still interested in this topic, i hope this information is some-what useful. It is only scratching the surface and i have a lot more specific info on these systems. However, there is much i DO NOT know, as audi doesnt give us all their details, only what they believe we need to know to diagnose and repair at the technical level.

    Im excited to be apart of this site and forum and im confident i will learn invaluable information about the operation of ADAS. Knowledge that will not only help me with my UGV project but maybe even help me move on to the next level in my career.

    • KCMastaPeace, That was extremely helpful! I myself do not have any ongoing projects involving radar, but am very eager to learn about it. 

      What I think is important is the 'hackability' of these units. In other words, if the system uses too much proprietary hardware (e.g. custom chips) and software (e.g. custom protocols), then it will be of virtually no use. Maybe you can give us a hint about the hardware, as you have done with the software. I understand that you might not be able to tell us everything, but maybe you can at least tell us what kind of chips are there (i.e. FPGAs, microctonrollers, industrial PCs, etc.)

      I believe others will have more interesting questions, but that's what came to my mind. 

      Thanks again!

      • I will try to answer questions the best i can based off the materials and courses ive received from audi and field experience. Unfortunately, processor, micro controller information is not typically info they disclose or teach us about, as they most likely feel it is not necessary for technicians. Unless it is to advertise or brag. For instance, they touted NVIDIA as the new A3 MMI GPU supplier. That is a pretty rare case though, most likely done because of the familiarity of the NVIDIA brand. 

        If i want to know what chips the modules use i simply disassemble the unit and google the chips and normally find a pretty good amount of information on them. I have not got a hold of a adaptive cruise sensor/module to disassemble yet so i couldn't tell you what chips it uses. I have, however, taken various other modules apart and got information on those chips. Based off the amount and type of information ive found from other modules chips, it doesnt APPEAR the hardware is proprietary. It gives the impression that the chips (based off the chip part or model number) can be used in more than one application and were not developed exclusively for either audi or the manufacturer of the control modules used in audi vehicles.

        I think the component protection is what needs to be worked around.

        Until i get a hold of an adaptive cruise sensor (they seem to be pretty resistant to failure, have yet to replace one), i will be working with the lane detection camera that is used for the lane departure warning system, much like this one.


        Lucky for me, i acquired this $900+ camera module because the windshield installer broke one of the mounting tabs that secures it to the windshield bracket so the camera, while fully functional and undamaged itself, could not be calibrated. Normally parts that are warrantied for defects get sent back to the manufacturer. Since this part was damaged it is unwarrantable and is to be disposed.... But I wasnt about to let this treasure end its life in a landfill. It may or may not make its way on to my project, but i have the option. Im more interested in getting my hands on a radar sensor. At that point, even if defective, i could tell you the manufacturer of the chips with model and part numbers.

  • An interesting development going around the tech news websites is this rear facing radar for bicycles

    There's not a lot of detail but the "Open API" claim is encouraging.

This reply was deleted.