I have little experience with pyproj, but I want to achieve the following task:
I have a trajectory of a robot, given in lat/long coordinates which I want to convert to x/y Coordinates. And I want to do this using a "flat" cartesian coordinate system originating at a lat/long combination of my choice. I realize that this projection only works for a small area, but that is okay with me, as the area I am looking at is small (<10km in all directions.)
Here is what I achieved so far, which is a transverse mercator projection (or so I was told).
[![Robot path in projection](https://i.stack.imgur.com/gxYgV.png)](https://i.stack.imgur.com/gxYgV.png)

I have used the following code.

```py
import pyproj as proj

crs_wgs = proj.Proj(init='epsg:4326')  # assuming you're using WGS84 geographic
    crs_bng = proj.Proj(init='epsg:27700')  # use a locally appropriate projected CRS
    # then cast your geographic coordinate pair to the projected system
    x, y = proj.transform(crs_wgs, crs_bng, s['gps_lng'], s['gps_lat'])

```

So this question is two-fold:

1. Which Projection do I use to achieve a local flat cartesian coordinate system
2. Howto define this projection at my given lat/long combination

I was told to ask this question in a new thread, [see my old question](https://gis.stackexchange.com/questions/330445/generating-custom-projection-in-pyproj). Also [a similar question has been asked](https://gis.stackexchange.com/questions/316556/creating-a-custom-flat-projection-definition-in-proj4), but it seemed to be too unspecific to be answered.