RC Valve Controller Development

[Rapidrory]

Been working on a load of designs to be sent off for professional printing. Currently got:

Feather ESCs
2 channel valve switches
Servo controller boards
Nanoweight ESCs
Signal mixer with built in Gyro and auto signal inversion (for when invertible robot's are flipped)
Antweight ESC with built in Gyro and signal inversion.

Any suggestions for bits of electronics hardware welcome; I still have a bit more space on the board. I will only be printing 10 of each, but can print more if people are interested in one type, though I will likely only sell limited numbers of the FW ESCs and Gyro boards as they'll probably be a right pain to build :L Also, most of these are currently just untested layouts, so don't be too surprised if I pull items off the list after the boards arrive..

[Eventorizon]

I had been considering using an Arduino to make an electric Axe controller with a couple of modes, switched between using the AUX 1 on the transmitter. Mode 1, you use the rudder stick to manually fire back and forth. Mode 2, you use the throttle stick to control the speed the axe fires automatically back and forth. I was going to use some small switches near shaft to act as limit switches so the axe knows where it is. However I am not sure its actually that simple, but I will give it a try regardless, I am sure you can come up with something better.

[Rapidrory]

Axe controller's not a bad idea actually; I need one anyway for my next feather.. I'll probably just change the firmware on the Servo controller boards for that though as they're fairly similar in hardware requirements. It would likely be a time based system where the axe fires at full power for an adjustable amount of time based on the potentiometer on the board. I'll see about having it switchable to manual control on the rudder channel too as that's something I'd quite want for self fighting... May also be able to do limit switches, but I'm not sure I'll have enough IO pins for that!

[Max]

Just a thought on what Terry said about adjustable timing, you said you couldn't have a potentiometer as you lack an analog input pin, but I guess you could have an ordinary push switch as the input, then you could for example have it so you press and hold the switch for 2.5 seconds or 25s and that would correspond to the valve being open for 250ms, or have it so you press it multiple times with each click being an additional 10ms of open time. Obviously this is harder to make precision adjustments than with a pot but perhaps could be an option?

[Rapidrory]

Not a bad plan. However I just bought a PIC with analog inputs instead :P

[Rapidrory]

The controller boards arrived back a while ago but I'm yet to properly do anything with them; I've made up a few of the servo controller boards to do several things other than control servos (the one I used to do the endstops for Richie's lifter is shown below), one of the 3 channel valve switchers was sent for testing in a heavy without much success yet (though I haven't had it back for diagnostics), and the other boards I haven't had the time nor bought the parts to populate them.



What I have been doing is working on the new heavyweight controller prototype, which is just a scaled up version of the featherweight one with 2 Fets per channel rather than one, and much better and safer driver circuitry. I say prototype as just after sending them for printing I realised a load of flaws in the design that need improving, but it should still work fine albeit not at such a high current rating as I'd hoped. This version also includes the facilities for testing out current limiting, which should help keep everything from catching fire. Having looked at the ragebridge controllers I've been impressed at what a powerful tool current limiting can be (60A controller running a heavyweight fine).

As such, I realised that it could be possible to create a plug in board for other controllers to add in adjustable current limiting. This would plug in between the power supply for the ESC, and also the signal line. It would be mainly aimed at the TZ85a, and would have an upper current limit setting of around 80A. It could be used to reduce the risk of flaming your motors on stall or a large overvolt, as well as possibly safely driving bigger motors than you otherwise could (see 60A ragebridge running 1000A startup current motors). Just a possibility; curious if there'd be much interest in me making such a thing..

[Ellis]

A small/lightweight in-line current limiting board would certainly be interesting. I'd like to current limit the Dewalts in T3 so I can go to 6s and keep the smoke in, but don't have anything like enough space for an RB2.

[overkill]

What method are you thinking of using to limit the current?

[Rapidrory]

It would be a closed loop system, so would take current readings with a low resistance shunt, and then use the readings from that to adjust the maximum RC signal to the ESC accordingly. Unfortunately it won't be possible to have a very high refresh rate seeing as the RC signal updates at a maximum of about 100Hz, but it should still be plenty enough to stop things frying so easily.

[Rapidrory]

Ok, so back on the original topic of this thread, the valve controller has now been successfully tested for a few events in Dystopia (the valve controller worked fine, even if the rest of the machine occasionally didn't :L ). This was running 2 valves on separate channels at 36v, so fairly typical usage in a heavyweight, and there have been no issues with it. I've just bought in a stock of components, so these things should now be ready to sell.

Prices are looking to be:
£15 for a single channel switch
£20 for a 2 or 3 channel switch (uses different board)
£2 UK Postage (will have to check price for further a field)

Single channel default operation will be on for up, and off for centre stick and down.
Two channel default will be channel A will be on the up stick, channel B will be on the down stick, and both will be off on centre stick.
Three channel default will be channel A will be on the up stick, channel B turns will be on centre stick, and channel C turns will be on the down stick.

I can set up the channels for any combination of up, centre, and down that you like, so just tell me what setup you want. Do note though, I haven't tried firing multiple burkets on one channel with this at once, and although it would probably be fine, if possible it would probably be safer just to use two channels set to fire at the same time, so bear this in mind when ordering.

I don't have a new picture, but I'll just repost the one of the single channel switch from earlier in the thread as they haven't changed at all:


If you're interested, either PM me or email me at rapidrory@gmail.com. Payment is via PayPal to that same address.