Motor Turns on by Itself


#1

Whenever I connect power to my ROV a thruster automatically turns on. I noticed that the insides of the motor are a bit rusty, could this be the problem or is it doing this because of something else?

Thanks


#2

Have you calibrated your ESCs yet?


#3

Yes I have


#4

Hmmm... I would have suspected Brian's idea as well. There are two things that need to be done to each ESC: programming and calibration (in that order). I might suggest re-calibrating the motor that spins on its own, otherwise, perhaps try refreshing the browser while it's spinning and see if that changes anything.

Let us know how it works out!

Eric


#5

I realized that I programmed the ESCs, but I did not calibrate the ESCs ( I didn't know there was a difference). However, when I turned on ESC 1 and ESC 2 separately, ESC 3 would turn on as well. Also, what happened once, was I tried calibrating ESC 2 and then the entire controller board shut off. I had to disconnect the DB-25 connecter and plug it back in.


#6

Hi Sam,

We are currently dealing with this same issue. I am beginning to think it is due to a damaged ESC. I am running 2.5 board with 2.5-5 image.

I was replacing a motor and wanted to check it out before installing it so I clamped it to the side of the plastic chasis. Everything seemed to be working so I made the mistake trying to reprogram the ESCs while the PWM connectors were still in place.

Halfway through the programming steps, the motor went hard on and caused the motor to break free from the small clamp. Silly me, I took off the motor rotor and thought the hardover would clear when I recycled the rov power. I redid the programming steps and sure enough smelled buring plastic! The motor still had a hardover command and had no backemf to cancel the command voltage and the motor became a toaster with the high current flowing through it. I branded the side of the rov but the motor still tests good.

So... can you mess up an ESC by programming it with a PWM connected?...possibly but there might have been some other cause of the hardover by the arduino code.

I tried varius things to restore the ESC. I unsoldered the motor and was able to complete the programming steps without trouble with the PWM cable disconnected. However, with the motor reconnected, the hardover still occurs immediately at power up (PWM in) (I think it even occured with the ESC switched off.) If I disconnect the PWM and power up with the ESC off, the motor doesn't run.

The hardover at power up might be caused by a calibration error but I see no way of performing the calibration since the slide controls in the diagonostic display don't work on the motor. I suspect that the ESC goes hardover when it senses 5 v on the PWM rather than some command on the white signal wire. I also had some weird crosstalk between the ESCs. When I plugged in the pwm cable of a good ESC the bad ESC would run. But I am unclear about the exact sequences.

Today, I ran into another little problem. None of the ESC have power on them , but beaglebone etc are operational. So the ESC disconnect discrete is probably shuting them off.

Question to Walt/Brian: It appears that this discrete is controlled by the arduino. Does it cut out at below 11 volts and is there an overcurrent dectector that also activates the discrete. Our batteries are slightly below 11 volts. It would seem that a discharge cut off should be somewhere between 3v/cell to 3.2v/cell with the lipo's. So 11 volts should be ok, right?

I will try with override enabled on ESC disconnect and also try with newly charged batteries next time I get to the rov


#7

ok....openrov back running again.

ESC power was disabled because Arduino code was corrupted. I reimaged the arduino from the cockpit and now the ESCs powered up as usual again.

With cockpit software working, the hardover was fixed by recalibrating the ESC.

Note: The ESCs can get into an uncalibrated state that is very unusual. As I mentioned before, the problem ESC goes hardover as soon as a any 5v is applied to the PWM bus. I.E. if all motor ESCs are turned off the motor stops. Then, if any of the ESCs are turned on, the problem ESC runs the motor hardover even though its ESC switch is in the off position. Wierd. This is what made me think the ESC had failed.


#8

Hi Chris:

Glad you got your stuff working.

As you noted, some weird things can happen when there is just one ESC turned on. This is because of the way the power (servo red wire) is run in the gang of servo connectors on the Controller Board. Once you turn any ESC on, the BEC in the ESC feeds 6V power back into the servo power buss, and into the BEC output of the other ESCs. This can lead to some strange behavior at times, which you found out.

We have pondered how to make the servo power / BEC wiring different so that this doesn't happen. But we haven't come up with an easy way of doing so that will work for all the different use cases of the board. The controller board is designed to support many different designs, not just OpenROV 2.x specifically.

If during debugging you have issues with ESCs doing weird things, the best thing to do is unplug its servo leads from the Controller Board until you get it sorted out.

-W


#9

Regarding the BEC simultaneously hooked to the same bus. I couldn't think of any better way other than giving each servo port its own two way jumper that allows it to get power either from a BEC bus or an electronics board source. If no jumper was in place the red wire would not connect to anything. This would give the versitility you desire but at the cost of one new jumper pin/servo. Probably not worth the trouble.

It always concerned me that having multiple BECs connected would cause a problem if the voltage regulators were slightly mismatched but seems that the Turnigy handles this ok. Maybe they have equalizing resisters built in.