Posted 23 December, 2022

Just over a year ago I made a radical change to WallE2’s form factor to improve it’s turning performance. Since then I have been making other changes and improvements to WallE3, including a recent successful effort to improve WallE3’s ‘rolling turn’ capabilities. Based on that, this post describes a similar effort to improve WallE3’s ‘spin turn performance.

To date, WallE3’s ‘spin turn’ performance has been lackluster at best. Rather than turning smoothly, it tends to ‘motorboat’ it’s way through the turn, starting and stopping several times through the turn. After achieving some success with smoothing out the ‘rolling turn’ feature, I decided to take another crack at ‘spin turn’.

I started by creating yet another part-task program that does nothing but support spin turn operations. This program accepts a set of parameters, calls the existing ‘SpinTurn()’ subroutine to execute the specified spin turn, and then returns to the parameter entry state for another go.

The starting point for the effort was a 90º CCW turn at 45º/s, with PID = (1,0,0). As shown below, this produced a nice smooth turn, but way too slow (17º/s vs 45º/s):

After a coupe of dozen trials, I gradually worked my way up to a ‘final’ PID of (0.7,0.3,0). Here are plots and videos for various turn lengths and rates.

After running these tests, I decided to see how WallE3 would perform on carpet with these same settings. As shown below, carpet performance was pretty much identical to the smooth surface runs.

So, with much better performance now for both the ‘rolling turn’ and ‘spin turn’ features, it is now probably time to revisit the whole wall-tracking thing, and see if I can achieve better performance than in past efforts.

Stay tuned,

Frank