Running SLAM system on AirSim

[xuhao1]

Hi Guys,
I have successfully run a well-known visual-inertial system VINS(https://github.com/HKUST-Aerial-Robotics/VINS-Fusion) on AirSim (which is amazingly good!) based on the ros package which verified the possibility of simulating my own aerial swarm in Airsim.

However, I found a few issues about the ros package;

1. The Unit of the angular velocity is wrong. The data from airsim is already rads
2. The coordinate system seems is confused
3. The unnecessary process lock lower the whole performance, with the useless lock we can only get IMU for ~20hz(because IMU always wait for images....For slam system we need high frequency IMU and low frequency images and depth), without we can get 300hz!
4. The ros package used simGetImages with single request a few times, which will be slow when we use a stereo camera. Change simGetImages with multiple requests will be much faster on mutliple cameras!
5. The ros package use soft time stamp (the receive ros::Time::now) instead simulation time
6. Nowhere to set host IP

For problem 1. 5. 6. I have submit a pull request #2368,
For problem 234, my modification loses the generic but it solves the problem, gives me 20HZ stereo images and 300hz IMU on a remote notebook and successfully running VINS-Fusion in AirSim smoothly, here is my repo https://github.com/xuhao1/airsim_ros_pkgs.
If you are interested in running VINS or other slam methods, you can have a try. The configs file for VINS and settings.json for Airsim have been placed in vins_airsim/ folder

[simengangstad]

We've worked some with VINS in AirSim as well, but haven't gotten any good results. Do you have any numbers on how much the position drifts compared to ground truth from your current setup?

[xuhao1]

Simen Gangstad (@simengangstad) , there is drift. However, drift is normal for VINS-Fusion without Loop Closure on. If you are interested in it, you can have a try with my package.

[Beniko95J]

Hi, may I ask how did you achieve 20Hz stereo images? I am also trying to run VINS-Mono on AirSim, and when I set the image resolution to 288x512 (original 144x256) and set the timer to save images every 0.05 second, I can only obtain 3Hz 288x512 images through its image apis. Do you have any idea about this?

[kminoda]

I am having similar issue in similar situation, which is to run VIO algorithm on AirSim ros pkg. I want to change frame rate of camera and IMU.

I assume that its "update_airsim_img_response_every_n_sec" in here that corresponds to camera frame rate. But it doesn't make any difference. Camera frame rate is still 3Hz even though I set the value to 0.1 (so it should be 10Hz).

I modified airsim_ros_wrapper.cpp according to this repos, but it doesn't solve the problem either.

Does anyone know how to solve this problem?

[dssdyx]

XuHao (@xuhao1) Which coordinate did you transform imu link to? NED to ENU or other? I see your body_T_cam in vins yaml, is corresponding to ENU. The linear vel from NED to ENU should be (x,y,z)->(x,-y,-z),but your code is (x,y,z)->(-x,y,-z). I feel really confused.

[manthan99]

I am also having a similar issue with the published rate. I tried modifying the code according to this repo but I am only getting a publish rate of around 5 Hz for the camera and 10 Hz from IMU. Changing the "update_airsim_img_respone_every_n_sec" doesn't seem to increase the rate.
Any solution to increase the rate?

I am having i7-6700HQ, 16 Gb ram and Gtx 1070

[rajat2004]

Could you check the parameter DrawDebugPoints in Lidar in the settings.json? If true, that causes a huge slowdown in the current latest binaries. Fix #2614 has been merged into master, but the problem is there in the binaries. Just change that to false and should improve the rates
There's also another WIP PR #2472 to increase the camera rate

[manthan99]

Rajat Singhal (@rajat2004) I am not using a Lidar. Here is the settings file which I am using [Settings.json]

Though the rate significantly improved to 20 Hz upon using the "NoDisplay" viewmode

[rajat2004]

Mentioned about the Lidar since that was causing problems with people trying out the ROS package tutorial and all. Using NoDisplay will definitely improve the rate since rendering is less
XuHao (@xuhao1) It would be great to have a PR with your changes if you're interested

[manthan99]

There seems to be a problem with the sync of images from left and right cameras ( ~0.05 sec)
XuHao (@xuhao1) did you face this issue?

[kminoda]

Manthan Patel (@manthan99) It’s nice to hear that you managed to get images on 20 Hz by using NoDisplay mode.
Did you just change “ViewMode” to NoDisplay in the settings.json you posted?