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Inputs

Memory Params

Most mapd inputs use params in the location /dev/shm/params to read and write data between it and openpilot. In openpilot you can create an instance of params that reads and writes to the correct location using the following:

from openpilot.common.params import Params
mem_params = Params("/dev/shm/params")

Log Level

The log level for mapd can be set by writing to the MapdLogLevel param. mapd reads the normal persistent MapdLogLevel param once at start and checks the MapdLogLevel memory param each loop to allow for changing the level while the process is running. The default level is info.

The level should be written as one of the following strings:

  • debug
  • info
  • warn
  • error
  • disabled

Pretty Logs

By default mapd outputs structured json logs. To print in a more human friendly format you can set the MapdPrettyLog param to 1 (in openpilot this would be equivalent to put_bool("MapdPrettyLog", true)). mapd reads the persistent param once at start and checks the mem param location each loop to allow for changing the value while running. Setting the mem param to 0 will revert back to structured logging.

Position Data

To get location data into mapd you must write the gps coordinates to the LastGPSPosition memory param. Note that it will read the normal /data/params LastGPSPosition on initialization to pre-load the current area but after the first read it will always read from /dev/shm/params. The expected format for the gps position data is the following json:

{
    "latitude": -84.82069386553866,
    "longitude": 38.40504468653686,
    "bearing": 24
}

latitude, longitude, and bearing are all in degrees.

Download Maps

Maps can be downloaded in one of two ways, by arbitrary bounding box or by pre-defined locations.

Download by Bounding Box

To download an arbitrary bounding box write the bounding box to /dev/shm/params/d/OSMDownloadBounds (OSMDownloadBounds memory param) using the following json format:

{
    "min_lon": -84.82069386553866,
    "min_lat": 38.40504468653686,
    "max_lon": -80.52071966199662,
    "max_lat": 41.97787393972939
}

When mapd downloads the specified bounding box it will clip the given bounding box to regions of 2x2 degrees due to how the files are stored in the cloud. So for the previous example the actual downloaded region would be:

{
    "min_lon": -86,
    "min_lat": 38,
    "max_lon": -80,
    "max_lat": 42
}

Download by Pre-defined Locations

mapd contains pre-defined bounding boxes for ISO 3166-1 nations and US states/territories. The nation bounding boxes are stored in nation_bounding_boxes.json and the US states/territories bounding boxes are stored in us_states_bounding_boxes.json.

To download by nation you must write a json object containing a list of abbreviations from the nation_bounding_boxes.json file to /dev/shm/params/d/OSMDownloadLocations (OSMDownloadLocations memory param) using the following format:

{
    "nations": ["US", "CA"],
    "states": []
}

To download by US states/territories you must write a json object containing a list of abbreviations from the states_bounding_boxes.json file to /dev/shm/params/d/OSMDownloadLocations using the following format:

{
    "nations": [],
    "states": ["OH", "KY", "WV"]
}

Note that when downloading the locations the bounding boxes specified in the respective json files will actually be clipped to regions of 2x2 degrees the same as when specifying an arbitrary bounding box to download. Also, when the region completely surrounds another smaller region the smaller region will not be excluded from the download.

Target Lateral Accel for Curvatures

The default lateral accel used when calculating velocities for map based turn speed control is 2.0 m/s^2. This value can be configured using the MapTargetLatA param and memory param. The regular persistent param is only read once when the process starts, the memory param is read every loop to allow updating the value while the process is running.

  • A change of +- 0.1 m/s^2 results in the velocity being raised or lowered by about 1 mph.
  • In general I suggest picking a value a few tenths below what the max reported max accel for your car is in torque_data/params.yaml. I have also created a copy of this data in a slightly easier to read format here.