Added article about fluid motion control devices (#52)

src/conf.py

@@ -74,7 +74,7 @@
 
 html_static_path = ["_static"]
 
-notfound_urls_prefix = ''
+notfound_urls_prefix = ""
 
 
 def add_context_funcs(app, pagename, templatename, context, doctree):
@@ -94,7 +94,13 @@ def add_git_history() -> str:
                 context["page_source_suffix"]
             )
             commit_log = defaultdict(list)
-            for commit in repo.iter_commits(paths=filename):
+            commits = list(repo.iter_commits(paths=filename))
+            if not commits:
+                raise ValueError(
+                    f"{filename} exists but has no commit history. Please commit the "
+                    "file before trying to build the site."
+                )
+            for commit in commits:
                 commit_log["Date"].append(
                     f'<a href="{repo_url}/commit/{commit.hexsha}">'
                     f"{str(commit.authored_datetime)}</a>"

src/telescopemaking/fluid_motion_control.md

@@ -0,0 +1,18 @@
+# Fluid Motion Control
+
+For more information, check out [Ed Allen's talk from the 2023 Portland Alt-Az
+Conference][portland-alt-az].
+
+## Devices
+
+| Device          | Comment                                                                                                                                                                  |
+| --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+| FRT-E2/E9       | Useful for tiny scopes; have very low torque                                                                                                                             |
+| FRT-G2/C2       | Might be useful for small scopes, particularly with reduced ratio installation                                                                                           |
+| FRT-D2          | Might be useful for small-to-medium scopes with reduced ratio installation                                                                                               |
+| FRT-L1          | Might be useful for small-to-medium scopes with 1-1 installations or small scopes with reduced ratios                                                                    |
+| FRT-K2/F2       | Unsuitable due to motion/backlash from internal design/build tolerances (4 units tested)                                                                                 |
+| FDT-47A         | Useful disk-type dampers for small-to-medium scopes with 1-1 installations or larger scopes with reduced ratios. Have passthrough capability and wider temperature range |
+| FDT-57A/63A/70A | Similar to FDT-47A with 1-1 capacity capable of handling even larger scopes. These are physically larger bodied, and have larger square inputs.                          |
+
+[portland-alt-az]: https://www.youtube.com/watch?v=R3ZWMsKWNII&t=3470s