Hi, I’m trying to tune a catamaran boat with Ardurover 4.1. I follow the wiki guide to tune speed controller and it’s perform well.
But I have a problem with TURN RATE controller. My boat have good power motors, so it can achieve a turn rate of 150/180 deg/sec. I change ACRO_TURN_RATE to 150. Then I enable tunning PID on mission planner. But I don’t understand what is the relation between RC command and desired turn rate. I do a full left RC command and desired turn rate slowly increase. It takes some time to get to RC command value. The problem is that I can’t make tight turns. Is there a way to modify the RC turning rate command to desired turn rate behavior?



In general if the pilot gives maximum left or right steering input the desired turn rate should increase to the ACRO_TURN_RATE value. Two things to be careful of though are that the ATC_STR_RATE_MAX is the same or higher than ACRO_TURN_RATE. The other thing to check is the ATC_STR_ACC_MAX value. This could slow down the rate with which the desired turn rate increases.

Ok, thank randy. Can you point me out to the equation that relate the RC command input to the desired turn rate?
ATC_STR_ACC_MAX works from RC command input to desired turn rate or is it acting on the real TURN RATE of the vehicle?


The Acro mode code is here.

The get_pilot_desired_steering_and_throttle method is here.

The turn acceleration limiting (ATC_STR_ACC_MAX) is applied to the desired turn rate not that actual turn rate. In general in AP we call this “input shaping”. We try not to ask the controllers to do impossible things.