Autocar Firmware
An autonomous car firmware on Raspberry pi using Orocos-RTT toolchain and PREEMPT_RT patch.
For gazebo simulation, take a look at this repository.
Setup - PREEMPT_RT
The PREEMPT_RT patch has been applied by following the instructions from here. When I applied the patch, I didn't notice a very big improvement in cyclictest - sudo cyclictest --smp -p95 -m results but actually they are bad compared to the stock kernel.
Stock Kernel
T: 0 (11011) P:95 I:1000 C: 26495 Min: 6 Act: 27 Avg: 17 Max: 138
T: 1 (11012) P:95 I:1500 C: 17654 Min: 6 Act: 16 Avg: 18 Max: 143
T: 2 (11013) P:95 I:2000 C: 13231 Min: 6 Act: 14 Avg: 15 Max: 131
T: 3 (11014) P:95 I:2500 C: 10582 Min: 6 Act: 18 Avg: 17 Max: 961
PREEMPT_RT
T: 0 ( 8918) P:95 I:1000 C: 22816 Min: 9 Act: 22 Avg: 22 Max: 146
T: 1 ( 8919) P:95 I:1500 C: 15187 Min: 8 Act: 25 Avg: 28 Max: 134
T: 2 ( 8920) P:95 I:2000 C: 11373 Min: 9 Act: 23 Avg: 24 Max: 103
T: 3 ( 8921) P:95 I:2500 C: 9084 Min: 11 Act: 26 Avg: 26 Max: 133
Still it has to be analyzed what might be problem. With stock kernel, it should give nominal performance without any problems.
The above mentioned site also have some pre-compiled images in their github account which should function out of the box and can be used without compiling.
Setup - ROS cross compile
I was able to cross-compile normal c++ projects but was not able to do it for ROS. Compiling ros and especially orocos on Raspberry pi is not possible as it will take huge amount of ram. I tried it using an external flash drive as ram but it was very very slow.
So I used the approach here and setup a docker environment which emulates raspberry pi and since the directory structure would be same you can just copy and paste the /opt/ros folder from your docker container to Raspberry pi(thats what i did and worked without any problems.). It is a bit slow compared to the speeds you get when you compile normally but it is lot faster compared to Raspberry pi.
Note : Still under development.