Draw a curve with a curvature constrain?

Hi everyone,

I would like to know if there is way to have a curvature constraint while drawing a curve ?
I’m drawing path for a truck with a minimum turning (steering) radius of 8.9 meters.

Or is it possible to rebuild a curve with a minimum curvature ?

Thanks for your help


You may have two issues here.
If you want to draw a circular curve with a specific radius, use the Arc command

The second is if your drawing is for a building permit within a municipality, your design will need to meet their requirements. They will have these specific details for ingress/egress, minimum turning radius standards for different classes of vehicles, and will tell you what those requirements are. The drawing you submit to them for a building permit will need to meet their standards.

Depending how you are drawing your curves, you could use a simple grasshopper definition like this to highlight anywhere the radius goes below some limit, so you can adjust it:

radius_check.gh (8.8 KB)

thanks, that’s what i ve done but it’s just a pain to edit afterward.

Do piping/wiring tools let you do stuff like that I wonder?

In another life I had the issue where it was really super-duper easy to use freeform 3d curves to define shapes, but for production they needed to be approximated as arcs, and not 20 different arcs like the Convert tool gives, as few different radii as possible. I made a Python script that could fit a given set of arcs to a curve, long story short. It’s not in any state or would even be allowed for me to let people use, so…sorry I’m just notiing to myself where people have a problem it might solve.

Oh, so simple!

I use the same method as Daniel to spot all the radius who go below my limit value and then i simply fillet then with a radius equal to the limit value…

Thank you every one

Changed category to Grasshopper

what data do i need to put using
" Filleta curve at a parameter." object.

t=curve parameter to fillet at.

yes, thats the question.
what parameter goes in there?

trying to figure if any of these methods can redraw a fitting curve with 3degree minimum radius constraint.
tinkering with these 3 methods, still cant find a way. Curve radius constrait v1.gh (53.9 KB)

what parameter goes in there?

A curve parameter.

Parameter is a number along the curve between the curves domain extremes which represents a location along the curve. For instance, if your curve is reparameterized (a domain of 0 to 1) then t = any number between 0.0 and 1.0.