I want to create a rrt planner using custom kinematic constraints in a 3d map ,how to proceed with this problem?

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mukund shah 2021-12-13

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评论： mukund shah 2021-12-20

i have 3d occupancy grid map and now how can i define my custom kinematic constraints and apply rrt to this problem?

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Answer 1

Sandip Kumar 2021-12-16

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编辑：Sandip Kumar 2021-12-16

This example showcases how to use custom validator with stateSpaceSE2 object inside plannerRRT: https://www.mathworks.com/help/nav/ug/moving-furniture-in-a-cluttered-room-with-rrt.html

This should give you inspiration of how to do it.

ValidatorOccupancyMap3D uses the occupancyMap3D: https://www.mathworks.com/help/nav/ref/validatoroccupancymap3d.html --> there is an example on this page which shows how to use plannerRRT

Read more about create custom state spaces here: https://www.mathworks.com/help/nav/ref/nav.statespace-class.html

Read about creating custom validator here: https://www.mathworks.com/help/nav/ref/nav.statevalidator-class.html

Other motion planning example: https://www.mathworks.com/help/nav/examples.html?category=motion-planning&s_tid=CRUX_topnav (note only some of them use plannerRRT)

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Karsh Tharyani 2021-12-17

编辑：Karsh Tharyani 2021-12-17

Hi Mukund,

I think you have kinematic constraints associated with your state space which is derived from SE3. You might want to consider overriding the implementation of interpolate. I have a sample skeleton of what such a class (called ConstrainedSE3) might look like.

classdef ConstrainedSE3 < stateSpaceSE3

methods

function obj=ConstrainedSE3()

obj@stateSpaceSE3();

end

function interpolatedStates=interpolate(obj,s1,s2,ratios)

interpolatedStates=interpolate@stateSpaceSE3(s1,s2,ratios);

obj.constrainState(interpolatedStates);

end

methods(Access=private)

function constrainedStates=constrainState(obj,states)

%Replace below with your constrain implementation

constrainedStates=states;

end

Your implementation of constrainState should be used to kinematically constrain a state transition which is carried out by interpolate. You might also want to override distance in a similar fashion if the basic measure of stateSpaceSE3 is not the true measure of distance in your constrained state space.

We would also be glad to hear from you on your specific use case so that we can enhance this in a future release of MATLAB. For the same, please reach out to Technical Support https://www.mathworks.com/support/contact_us.html

Hope this helps!

Best,

Karsh

Karsh Tharyani 2021-12-17

plannerRRT is a geometric planner and since the state doesn't have any notion of time it is hard to encode it in the planner. Have you looked at plannerControlRRT?

mukund shah 2021-12-20

Yes but i dont know to edit the state propogator, I want to make a state propogator in Se3 space for a 3d bicycle model, I have the rotation and translation matrix but I am not getting how to edit nav. State propogator for this task

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