Working list of algorithms to include

[SteveMacenski]

Hi all,

I have a working list of planners / controllers that I've been compiling and I wanted to share them here for potential ideas if anyone's interested in developing / adapting one in particular. Feel free to ping me about this and I'll help however I can

Planners

• A* - holonomic robots or robots small relative to environment
• Dij. - holonomic robots or robots small relative to environment
• OMPL - non-holonomic and non-circular footprint robots, potential formulation to include dynamic obstacles [IN PROGRESS] state lattice and hybrid-A* supersedes
• GPS / cartesian route following - taking in a list of semantic GPS waypoints and issuing a path based on it to follow exactly. GPS waypoint navigation demo #1631 (comment). Or more generally a teach and repeat for non-GPS too. Teach via recording while moving or manual annotation.
• Hybrid-A* - non-holonomic and non-circular robots with smoothed paths
• Vornoi / potential field planner - for a robot to stay far, far away from things as its primary goal NavFn, Theta*, and other planners can be tuned to highly penalize costed regions. While these are easy to implement, the quality is low so its not a good addition for a modern stack. Very 1990s.
• Theta* - doing straight line planning based on LoS
• State Lattice - non-holonomic and non-circular robots, useful in analog situations as Hybrid-A* but for arbitrary motion models (omni, diff, non-cars, forklifts) Hybrid-A* meets this need, might be adding state lattice template node to smac
• non-zero via-point planning (e.g. calling a continuous, kinematically feasible planner from A->1->2->3->…->B and then adding them all to a single path) -- route server Route Server anologous to Planner Server #2229 ? Or new action interface in planner server to have multiple via-points to plan (!)

Controllers

• DWA - compute trajectories based on weighted heuristics
• TEB - compute trajectories based on optimal bands
• MPPI / MPC /Nonlinear MPC- compute trajectories by model simulation supporting high speeds. Exact path follower / dynamic obstacles in formulation in progress
• LQR/iLQR/CiLQR - "MPC-lite" is the easiest way to describe it supporting high speeds MPPI supersedes
• Pure Pursuit - following a carrot

Recoveries

• Spin - spin in place
• Backup - back up from pose
• Alerts - sound, lights, etc to alert obstacle to move too usecase specific
• Wait - wait out some duration or until event occurs
• Push - if you know its safe, push a thing out of the way too usecase specific
• Call for help - Slack, msgs, email, operations center request for assistance
• Clear - clear state, plans, and costmaps
• "Get out of here" - find some permissible path using a dynamically feasible trajectory to just get out of this area some fixed distance, if any way of motion is possible too usecase specific

feel free to comment to add more and how they're useful

[maxlein]

Is there some issue/repo to see the progress of these tasks here?
Like Graph / lane or Pure Pursuit.

[SteveMacenski]

Pure Pursuit PR should land this week. Graph/lane is not likely to be ready anytime particularly soon. If someone else is interested in working on that, very much so welcome to do so.

[soldierofhell]

Hi @SteveMacenski, as for Hybrid-A*, is there any draft on this planner? I'll need it soon, so I'm gonna do this, but it would be good to have some starting point (if there's any)

[SteveMacenski]

Its in progress, if you're interested in collaborating with the 3 of us to finish it, I'm sure we can find a place for you to help out!

I had intended to finish it months ago but had to drop it to do more community management tasks and unblocking other people. Starting next week I should be working on it again in a limited capacity that will grow as other existing commitments complete.

I'd love to hear about your requirements, needs, and uses to make sure it meets your needs.

[soldierofhell]

I did my first approch, but seems like A* is too slow on large grid. Does anyone know any efficient parallization of A* on CPU?

Its in progress, if you're interested in collaborating with the 3 of us to finish it, I'm sure we can find a place for you to help out!

I had intended to finish it months ago but had to drop it to do more community management tasks and unblocking other people. Starting next week I should be working on it again in a limited capacity that will grow as other existing commitments complete.

I'd love to hear about your requirements, needs, and uses to make sure it meets your needs.

Hi @SteveMacenski
A colleague and I have some spare cycles to help with Hybrid-A*. What is the best way to get involved?

[SteveMacenski]

Hi @Robomoco please join the slack with this link https://join.slack.com/t/navigation2/shared_invite/zt-gnsw70li-tUsWwB1C9h3FLIabNVvB~A and introduce yourself on the on-boarding channel. You'll probably want to join the hybrid A* channel and also give me a PM. I'm in the middle of working on that this week too so its a really good time to jump in since my head is in it.

We also have a bi-weekly working group meeting on Thursdays. If you go to the TSC ROS2 page, at the bottom there's a calendar. You can add yourself to the navigation2 meetings and there's a link there for the Google Meet meeting.

[SteveMacenski]

@soldierofhell the hybrid A* planner has been merged and ready for use!