Saturday, February 14, 2015

More control, Less "Outta Control"

Control Freak Redux

To introduce this post, we direct you to our last entry in which an infrequent problem arose during rapid control changes from forward to reverse and reverse to forward is discussed. Under certain conditions a brief shutdown was required.  Of course a shutdown is not a good option in real-life, real-time boat navigation. The partial fix was a brief hesitation during the actual change of direction via the MOG's joystick. Also, a thought (to be proven Feb. 8th) of reprogramming the Navitas electric motor controllers might completely cure the anomaly. Please review the previous blog entry from 1/29/2015 (You Gotta Know Where It's Headed) to fully appreciate the advances noted below.

A February 8, 2015 test of the reprogrammed Navitas starboard controller for its electric motor yielded only one thing to do and that was a planned fix anyway. The bottom line being, that none of the Navitas programable variables sent to the starboard electric motor controller’s brain (commutator/sensor circuit inside the motor's shell) made any change in its behavior. 

HOWEVER , when all settings were returned back to their original parameters, it was obvious that the one true improvement was the port side electric motor had been upgraded at eCycle headquarters and responded far better than the older type eCycle, starboard motor, being 'program' tested. It seems the improvement is in the updated commutator assembly inside the motor's end cap shell.

The comparison of the older (starboard) motor to the newer (port) motor in rapid response, now confirmed the new (eCycle modified) motor was superior for rapid forward and reverse changes. Furthermore, after nearly 7 minutes of fast reversals of direction, the new port motor never confused its commands. In fact, the only way that it erred was a very planned and deliberate super fast direction change, very difficult to perform without malice toward the motor. Even at that degree of rapidity, pausing the joystick for barely a second, allowed continued operation, no shutdown required.

All of the activity on the new port motor was much faster than reversing an internal combustion engine through a mechanical marine transmission, as well as better than the older starboard motor's response.

A video shows the test but does not show the joystick movement on the hand held remote control unit. One can hear the noisier reverse versus the more quite forward. If one listens closely, there is a change in the motor speed but the starboard motor (on the right of the video) stays in its previous direction, although the joystick drove the controller in the opposite direction (the direction change was not communicated to the electric motor’s brain (older type sensor), so the rotation of the propeller stayed the same, oops).

The motors are quiet but the camera erroneously intensifies their volume.
The video shown is from a Samsung Note4 cellphone.
So, the intermittent behavior will be fixed by removing the starboard internal electric motor and replaced by newer type eCycle electric motor, as was done to the port motor. Why was this not done in the first place? Because the designer needs to understand what causes the problem, what is a single fix, a combination of fixes and exactly where does the fix occur in the motor and/or system? As a designer/builder one needs to know all they can about the intricacies within a system, bring it to the point of failure and create a reasonable and effective remedy. In this case a combination of fixes were required to iron out the intermittent operation.

After the starboard motor is prepared and reinstalled on the outboard, a series of similar in water tests must be made followed by an actual sea trial...  again.

No comments:

Post a Comment