Minerva's environment is densely populated. People may move
fast, and in unpredictable ways. Even static obstacles often
cannot be sensed reliably. Avoiding collisions is of uttermost
importance for robots operating in public spaces. Minerva's
lowest level navigation module is the "Dynamic Window Algorithm"
(DWA), a method to navigation at high speeds in dynamic
environment. DWA enables Minerva to travel at up to 1.6 meters
per second (over 5 feet per second), while still avoiding
collisions with obstacles. At such speeds, the robot's inertia
is substantial. Minerva's collision avoidance module considers
torque limits when determining motion speed and velocity. To
cope with difficult-to-detect obstacles, the localization
modules is consulted periodically to extract from the map a set
of "virtual" sensor measurements, which roughly correspond to
positions of known obstacles or hazards, such as a nearby
staircase. The following picture depicts a typical situation.
Shown here is the robot (center) and the direct