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Olivier Bertrand authoredOlivier Bertrand authored
Tutorials
Average place-code vector homing
Homing with an average skyline vector consist of deriving the skyline or an approximation of it from the visual information. For example, ultra violet light is mostly present in the sky, and thus by summing ultra violet light along the elevation one may obtain the skyline. This approximation was inspired by the visual system of insect and has been succesffuly applied to model of homing (Basten and mallott), and robots (Thomas Stone).
Once the skyline have been optained, the center of mass of it is calcualted. The center of mass of the skyline is a vector lying in the equatorial plane of the visual system (due to the sumation along the elevation). The center of mass of the skyline was succeffully applied in simulation and robots (Hafner, Mangan).
The center of mass of the skyline, also refered as average skyline vector, at the goal and current location are compared by simple difference. The difference gives the homing vector, i.e. a vector proportional to the velocity of the agent.
Our agent needs to have a function to convert its current state to a motion. This function, velocity, can be added as follow:
On a grid
By restricting the agent motion on a grid, we can used a database containing images rendered at pre defined location (the grid nodes).
And initialise the senses of our virtual agent
Now we have to initialise an agent moving on a grid (i.e. a GridAgent)
at an initial position
a mode of motion corresponding to the grid used in the database
Finally our agent is ready to fly for a number of step or until its velocity is null.
In close loop
Catchment area of ASV
To calculate the catchment area of homing method for a given goal location, the agent should be displaced multiple time at different location, and obsverve if the agent returned home or not. If it did, then the point in space from which the agent started its return trip is part of the catchment area.
When the agent is restricted to move a grid, and its motion at a given place, only depends on the current surrounding, then to calculate a catchment area one only to build a graph of motion and check how many points converge to it.