Arduino proportional control of a piston tank

C-3PO...

things get even weirder when you throw in what i am doing, and what the Teensy is doing...  they are basically co-opting the software to work with the "almost the same" hardware, bending it far beyond what you would think is prudent in some cases to get their hardware support up to the same level as arduino's IDE support for arduino hardware is.

I have just been building another piston tank for the CSS Pioneer. (I will post a photo in the next day or so.)

I have been planning to use one of the smaller commercial H bridge units together with an Arduino for the proportional control. The software is giving some issues in connection with the failsafe (At least it failsafes too successfully, too often!) But just a reminder warning that this software has still not been used "in the wet" in a model.

The PIC version has been "battle" (Oh alright pond!) tested for a number of years.

More soon,

David

It is beginning to look as if the occasional glitches in failsafe are caused by power supply problems. Intermittent - the worst sort of problem!

David

David,
Do you use the BEC in the ESC or do you use a separate BEC?
I changed on one sub from using the built in battery elimination circuit on the electronic speed controller to a stand alone BEC. The glitches I was having disappeared.
Not sure if it was the ESC being glitchy or if I was taxing the built in supply. Remember to disable the power coming from the ESC (either cut or remove the red wire from ESC).
Peace,
Tom

Thanks Tom. This shows the setup - still a bit of a "lash-up".



You can see I'm using a Micro Gyro ESC. The BEC is well specified but I usually favour a separate switch-mode power supply, for the reasons you give. In this case, I'm trying to save space. The "issues" do seem to be triggered by servo movements.

There are still some other software issues though. The fail-safe occasionally doesn't!

David

A bit more investigation. Servo movements were causing the Arduino to reset.

I have disconnected the BEC in the Micro Gyro speed controller and moved to a separate switch mode power supply (this has some large electrolytic capacitors in it to buffer any voltage drop.)

This works better but I'm still getting occasional problems with the failsafe in the Arduino software not working. Interestingly the original PIC controller board is working well in these circumstances. (If you look back in the threads, this board was developed and built to be very tough and well protected.)

Some conclusions:

- It is interesting how often built in BECs in speed controllers  don't work well in submarines. Too much demand from servos?

- I will use the PIC controller board for now. (The sailing season is getting very close!)

- Still some work needed on the Arduino version of the software in combination with the commercial H Bridges  but that is a better winter activity! (I've made a note in Github to this effect.)

David

David,

i find that 99% of all ESC BECs that we use (car/boat escs with reverse) are built to handle the load of a single standard size servo... which basically makes them useless for anything other than a 1/10 scale or smaller r/c car.

Just to say that I have now tested this software in the "wet" in a real model submarine and it works well.

I have posted the latest software to Github, for anyone to use:

https://github.com/rdforrest/submarine-proportional-pistontank

This version includes a "winch" control option, developed  for something I'm working on.

I am still getting some problems with my Arduino Nano clones having code corrupted and having to be re-programmed.

(I have had the same problems with Nanos used with Tim S's Telemetry.)

I still think that power supply is the problem. I am using a separate power supply (I would never use a speed controller BEC) and I have recently moved back to analogue from switch mode but still with these corruption problems.

LATER EDIT> I have just checked and it was actually a switch mode power supply in the model. I have installed an analogue one now, so lets see.

LATER, LATER EDIT ! (March 2020) An analogue power supply failed to solve the corrupt code problem. However I think I may have solved the problem by using a genuine Arduino rather than a clone. This seems to be holding up well so far and without out all the input signal protection I had installed on the clone.

David