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microsoft / AirSim

Open source simulator for autonomous vehicles built on Unreal Engine / Unity, from Microsoft AI & Research
https://microsoft.github.io/AirSim/
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Clock speed doesn't work, timestamp is not synchronous #4310

Open Leon-Redfield opened 2 years ago

Leon-Redfield commented 2 years ago

Bug report

Hi! I'm using multirotor SimMode to simulate a drone flying in the village. And I'm using "Airsim_ROS_wrapper" to receive the messages from Airsim. There are two main problems:

  1. I tried to modify the clock speed in settings.json, but when I modify the value from 1 to 2, for example, 1.5, 1.7 and 1.9, the real clock speed shows like this picture: the config clock speed is different from the actual speed. clock speed-1 clock speed2 clock speed3

You can see, whatever value between 1-2 I use, the actual clock speed is always around 0.95. But when I modify this value to 2.0, the actual clock speed jumps to 1.76 like this: clock speed4

What I really want is to make the actual clock speed just at 1.0000 but I have no idea. My CPU is i7-10700, graphic card is RTX3070Ti. So just because of the problem above, I have the second problem.

  1. The timestamp of the simulation environment is not synchronous with ROS. In airsim_ros_wrapper, I use two kinds of functions to acquire the timestamp: airsim_timestamp_to_ros(msg) and ros::Time::now(). So I print the timestamps in the terminal, and the code is as below: lidar_msg.header.stamp = airsim_timestamp_to_ros(lidar_data.time_stamp); ROS_WARN("Compare the two kinds of timestamp"); std::cout << " The lidar timestamp is : " << lidar_msg.header.stamp << std::endl; std::cout << " The ros timestamp is : " << ros::Time::now() << std::endl; And the final result is that the difference between this two kinds of timestamps is bigger and bigger. I guess it is because of the clock speed of Airsim is not synchronous with that in ROS. timestamp

So all above, I want to solve these two problems, hope to get the solutions, thank you!

pie-leroy commented 2 years ago

Hello, How did you get around this problem? @Leon-Redfield

Leon-Redfield commented 2 years ago

Hello, How did you get around this problem? @Leon-Redfield

Sorry but I didn't solve this problem.

xuqingyuan2000 commented 1 year ago

I ran into the same issue, causing the lidar timestamp to be out of sync with the Imu timestamp. Can I use all ros::Time::now()?