I am trying to tune my new twin screw boat that uses skid steering and steerable kort nozzles to power and steer the boat. One of the modes I have setup is “Steering”. When this mode is selected, the props and kort nozzles behave as expected when directed to turn the boat left or right. Dry land testing however shiws that when the steering joystick is released and moves back to the neutral position the korts typically do not return to the neutral position and the props similarly do not fully return to the neutral condition (in the absence of any forward/reverse thrust this should result in neither props turning) instead they continue to rotate (in opposite directions) as if the boat were attempting to slowly swing about a vertical axis through its center. If I switch to manual mode, the kort nozzles move to the correct neutral position and the props come to a complete stop.
Has anybody else seen this behavior? Can anybody suggest a solution? I have spent a considerable amount of time cleaning up the wiring to eliminate electrical noise and the motors now change speed smoothly as the requested thrust increases/decreases.
This sounds like normal “Steering” bench test behavior. Normally the rudders, your nozzles, will behave just like your nozzles are. The motors still running a bit is probably because you are using skid steering and they are responsible to help turn the boat. This is why they are spinning in opposite directions. For giggles put it in steering mode and yaw the boat you will see what I mean. Your behaving as expected.
It’s possible we can improve support for this frame in a future release (it’s not particularly hard) but for now, the two methods of steering/throttle are quite separate and I don’t think they will interact well together so I think it’s best to either use skid-steering OR use the regular Ackerman steering/throttle.
To be more precise about the problem, the issue comes if the rudder is directly in the path of the motor. In this case the rudder direction must change depending upon which way the motor is spinning… or more precisely which way the water is flowing over the rudder. We do handle this reversal of the rudder if vectored-thrust is enabled but this only works currently for Ackermann style steering/throttle. If skid-steering is setup, the rudder will point in the wrong direction in situations where only one motor is spinning in reverse.