Transformations of instances of collection - problem with "origin"

Question

I have serious problems when I build complex machines from instances of collections.

Consider e.g. wheels/tracks of a Tank: Each wheel is instance of a wheel template which is a collection of individual meshes (rim, axel, disk, damper ... )

This instance is multiplied 12x (6 wheels on each side), and then transformed by translation (offset between wheels in the track) and scaling x=-1.0 to get mirror symmetry (left track, right track)

But If I move the whole thing everything breaks appart, as each instance moves in different direction according to different pose of its origin.

Before I was working with "Softimage XSI" and there were many tools to solve this

1. Global / Local and COG mode of transforms (using different coordinate system)
2. Tools to modify origin of collection without moving the meshes inside the collection

I cannot find such tools in Blender 2.8

Answer 1

I don't think your coordinate space is at fault per se, I think you need to mess with your operating sets. By description alone it sounds like you have your active Transform Pivot to be "Individual Origins", "Median Point" sounds like what you want.

You can mess with your working translation space by clicking the "global" directly to the left and choosing something else.

Something else you might want to do is parent all your pieces of your object to something, either the root mesh, an armature, or an Empty. This will allow you to conveniently move and animate the whole set by moving the parent.

Lastly: if you mirror by duplicating and scaling by -1, you will also need to flip the normals depending on usage. It is oftentimes better to use the Mirror modifier instead, it is more convenient and stable.