# How to make RRT to work for dynamic systems?

I want to make path planning algorithm for a quadrotor with RRT in my thesis. I have searched lots of articles and come up with the concept of "dynamic RTT" and one of the articles has a title "kinodynamic RRT*". I have emailed the author of the article with no response.

The main point that I couldn't understand is, we need to sample random state for dynamic RRT like 2 position and 2 velocity values for planar vehicle or an angle and its rate in case of 2D-quadrotor.

How should the samples be so that speeds and positions does not confused and when should I consider the saturation limits of the actuators or vehicle acceleration limits.

I can't understand how to handle what if two consecutive samples for positions are A(0,0) and B(10,10) this needs positive velocity at the point B but sampling can cause negative velocity. Am I wrong?

Other issue is, how should the control signal be determined so that it can be applied for duration of delta t to move as close as possible to the sampled point. I am not sure how to determine the input or move the vehicle.

Do I need optimizations so that it can reach to the sampled point in shortest time possible?

Please let me know if there is a missing part to be understood.

Wish a hopeful new year.

• What is RRT? Can you link to any of the papers, or at least post the title and author(s)? – Chuck Dec 12 '16 at 13:16
• google.com.tr/url?sa=t&source=web&rct=j&url=http://… this is one of the articles – freezer Dec 12 '16 at 13:54
• This paper should provide enough info to implement kinodynamic RRT* arl.cs.utah.edu/pubs/ICRA2013-1.pdf – 50k4 Dec 12 '16 at 14:41
• I have this article and the author Dustin Webb is the one who I sent an email. I really couldn't understand the cost function parts while I have the code related with the article. I can't get the point where I am considering the saturations etc. – freezer Dec 12 '16 at 23:27