Progress Review 9

MRSLAM

• Testing and tuning in real life
• Initial testing with 4 robots – identified initialization issue
• Modified Ray Casting behaviour to fill in all free areas

Navigation

• Hardware testing for Lazy Traffic Controller
• Tune the controller velocity calculation frequency to the execution frequency of the robots
• Since differential drive robots don’t immediately achieve commanded velocity, use feedback velocity (calculated from change in position of the robot) for velocity obstacles calculation
• Addition of new term in cost function while scoring velocities to reduce oscillations
  • float penalty = RVO_SAFETY_FACTOR / min_t_to_collision + dist_to_pref_vel + dist_to_cur_vel
• Static obstacle avoidance
  • Latencies in real life / localization errors causes robots to sometimes collide with obstacles
  • Adding static obstacle avoidance increases robustnesses and prevents crashes

Task Generation

• Frontier Exploration
  • RRT-based frontier generation
  • RRT expands from robot starting position into free space
  • When a node connects into unknown space, it is considered a frontier
  • Possible frontiers are then clustered and filtered to prevent redundancies
• Challenges:
  • Improve filtering based on information gain
  • RRT does not update with map loop closures
  • How does this scale to larger maps?