RMP220 question about yaw rate discrepancy

[ChrisC]

When trying to send a yaw rate to the RMP, the user defined feedback bitmap(at element 57 of the returned array) returns the target yaw rate to be 3 times greater my desired yaw rate. Is there a reason for that?

[sdnalloh]

During testing, I found that yaw_rate_target_rps (page 62 of the RMP 440 SE User Manual) quite accurately represented the yaw rate I commanded.

I recommend you check your units and conversions. This feedback variable is in radians/second.

[phussey]

A very important note is that the yaw rate command is normalized to the maximum yaw rate. Meaning the input command is unitless (-1.0...1.0). Since the default max yaw rate is ~3 rad/s; commanding 1.0 would result in a yaw rate of 3.0 rad/s. This is also true for the velocity controller, obviously different scaling. This information can be found in the manual.

I think if it were a conversion issue it would be off by a much larger factor (180/pi = 57.29578), or smaller depending which side of the conversion you're on.

[Phillip.Wong]

Thank you phussey and sdnalloh! Your posts are incredibly helpful.

That was exactly my problem. I wasn't aware of the normalization happening, so now I have excellent control over the yaw rate/angular velocity. After some testing, the velocity inputted isn't normalized/scaled. Its not a problem since I can adjust accordingly, its more of just an observation. However, it could be possible its still an error on my end.

[ChrisC]

Velocity commands are also normalized against the configurable parameters. Have you had a chance to review the motion command structure which is defined on page 39 of the User Manual - RMP 440 SE?

If the defaults were used during installation the document will be located in the following directory: C:\Program Files\Segway\RMP_Applications\Documentation