Tutorial¶

Survey¶

First make a Survey object. An optional name can be specified.

from wadl.survey import Survey
# make survey object
name = 'stanford'
survey = Survey(name)

Geofence¶

Next get the geofence file (csv).

# files are assumed geofences (ID, lat, long)
file = <path_to_geofence.csv>

Home¶

Most surveys will have a predetermined takeoff/landing location known as the “home” point. A set of these key points can be added to the Survey.

keyPoints = {"pt_0": (LAT_0, LONG_0),
             "pt_1": (LAT_1, LONG_1),
             }
survey.setKeyPoints(keyPoints)

Task¶

Each survey is made up off a set of geofences, each geofence is referred to as a Task and expects a home point as the key in the keyPoints dictionary. Home points can be shared over multiple tasks. if no home is set, the default location is the most south eastern point.

survey.addTask(file,
               step=100,
               home=KEY,
               routeParameters=routeParams,
               )

Where step is the desired grid spacing.

Planning¶

Visualize¶

To visualize the current survey and tasks use

survey.view()

Plan¶

To plan and plot the survey use

survey.plan()
survey.plot()

Routes are planned in such a way that the segments between the home and coverage section are at a different altitude than the altitude of the survey.

The routes are composed as follows: home - transfer to site -coverage path - transfer to home - land (optional).

Parameters¶

Route Parameters¶

As seen above, each task can have custom route parameters (flight speed, altitude). To set the parameters, import the RouteParameters object and set the desired values. The below values are the defaults

from wadl.lib.route import RouteParameters
routeParams = RouteParameters()
routeParams["limit"] = 13*60  # s flight time limit in seconds
routeParams["speed"] = 4.0  # m/s
routeParams["altitude"] = 35.0  # m
routeParams["xfer_speed"] = 12.0  # m/s
routeParams["xfer_altitude"] = 70.0  # m
routeParams["xfer_ascend"] = 5.  # m/s
routeParams["xfer_descend"] = 4.  # m/s
routeParams["land_altitude"] = 30  # m

Solver Parameters¶

WADL uses the Z3 SMT prover from Microsoft Corporation to encode and solve the underlying route planning problem. Certain settings can be changed to better suit the user. To set the parameters, import the SolverParameters object and set the desired values. The below values are the defaults.

from wadl.solver.solver import SolverParameters
solverParams = SolverParameters()
# the initial size of each subgraph, decrease for less powerful computer
solverParams["subGraph_size"] = 40
# the initial offset of each subgraph path, increase for faster solve time (less efficient routes)
solverParams["SATBound_offset"] = 2\
# timeout (in seconds) of each individual SMT problem
solverParams["timeout"] = 60\
# number of SMT problems attempted for each subgraph, limit increases by 1 for each infeasible subproblem
solverParams["maxProblems"] = 10

After setting the solver parameters set them by calling the .setSolverParameters() method of the survey object.

UGCS¶

WADL has support to export route as a mission.json file to UGCS.

from wadl.mission import Mission
mission = Mission(missionParams)
mission.fromSurvey(survey)
mission.write()

This creates a mission.json file that can be loaded into UGCS. This will also group the routes by sector to make it easier to field a multi-robot survey. This will also modify the transit altitude of the UAVS. The parameters can that be set are below.

UGCS Version¶

To set a UGCS version you can call

mission.setVersion(major, minor, build)

Where the major.minor.build is your version of UGCS

Mission Parameters¶

To set the parameters, import the MissionParameters object.

from wadl.mission import MissionParameters
missionParams = MissionParameters()

Autoland¶

Auto land the UAVs at the home position

missionParams["autoland"] = True

You can also set a pre landing altitude where the UAV will go to this altitude after the last point in the route

missionParams["pre_land_alt"] = None  # m

Route Organization¶

Once routes are found, they can be organized and encoded into a mission JSON file for UGCS to open. These options are for large surveys with multiple UAVs where coordination of the routes and their sequence is needed

Group Routes:

# group the routes
missionParams["group"] = "home" ## other option is "task"

Sort Routes:

# sorting routes
# sorts the routes within a group with the following strategy
missionParams["sort"] = "angle" ## other option is "east" or "north"

Assign Routes:

# assigning routes
# routes can be assigned to bands either sequentially or sector
missionParams["assign"] = "sector" ## other option is "sequence"

Offset Routes¶

Offset the start and end of the route a certain amount from the home point, this make it easier to have multiple UAVs have the same home point

# offsets the takeoff location by this distance in m along the first segment
missionParams["offset_takeoff_dist"] = 0

# offsets the land location by this distance in m along the last segment
missionParams["offset_land_dist"] = 0

Altitude Bands¶

You can set the number of bands to split (normally the number of UAVs used) the UAV transfer altitude into as well as the starting transfer altitude and band separation altitude

missionParams["N_bands"] = 1

# the started altitude in m (agl)
missionParams["band_start"] = 50

# the altitude band separation step
missionParams["band_step"] = 10