Hello everyone,
Now I have problem on instance rotation objects. When the object fall down, it was not over the ground as I wanted. Sometime it was below or equal the ground. I uploaded image below.
If any has experience or know how to fix it, Please kindly help 
Hi tykoy,
in my opinion it will never look good with particle instances and rotation. You should use a plugin like bullet to simulate collisions on hard- and softbodies.
Cheers
Hmm,
yea for something this scale, I’d use rigid bodies. Instancing would be better for smaller objects, and if they need to collide - instances are better if the object is more spherical.
If these are nParticles, I believe you can change the collision shape to be a cylinder, which would be much better in this situation as your objects are more cylindrical than they are spherical.
See if you can use nParticles for this (instanced of course), and play with the collision settings.
Good luck! Also, I dislike when people say this but you may want to look at Houdini for this kind of thing. It’s a heck of a lot more approachable than it was a few years ago!
Best,
cw