[Bug] Unit 3: Impossible to create a map

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Error details

I'm trying to create the map following the commands, but it's clearly impossible. Doesn't matter if I go fast or superslow, the robot jumps around after a while and the map is useless. This is really frustrating. What do I have to do?

Hi @Marco_Monforte ,

“Impossible” is a strong word. I am sure it is not impossible to do things in ROS 1/2.

Coming to your issue, mapping usually suffers when certain conditions are not met during mapping process.

  1. Loop Closure - if the mapping algorithm is unable to perform loop closure, then the mapping or the map will be bad.
  2. Speed of robot - moving the robot too fast and turning the robot too fast will make the robot go “dizzy” during mapping process.
  3. The odometry frame has drifted due to position or velocity errors.

To avoid all those and have a good mapping, the following are the best-practices.

  1. Map the environment slowly and steadily.
  2. Don’t use fast linear and angular speeds.
  3. Use a reasonable map resolution setting that is not too fine or too coarse.
  4. Try not to collide with any blocks during mapping.
  5. Mapping process is assumed to be partly or fully supervised process. Since you are the person physical moving the robot to map the environment, please be patient and map slowly.
  6. Robot “jumping” position is commonly referred to as “robot kidnapping” - this happens due to bad odometry or fast speeds or lot of collisions.

If you follow the above 6 practices during your mapping, I am sure you will get a quality map.
Also, look into your mapping config file to see if you can modify any values that will make the mapping process better - there are so many variables and I can’t say for sure which variables have more impact on the mapping process.


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