I am designing a Radio Controlled model, and have a fairly comlpex control system in mind. On the purely electronic side of things: I have 2 motors and want to vary the total power going to them, and the difference between them. To save weight I'd like to do this with digital electronics (plugged directly into my receiver) rather than variable resistors and servos. I also expect to use brushless motors so couldn't do that anyway. I'm not going to go into any more detail now anyway since I don't know if anyone here can help me. But, if you can, then please let me know. Even a suggestion for somewhere else to ask will be much appreciated. j
you could program a PIC chip to do PWM on two outputs, and make some kind of maths function that will create a differential output across both of them, if that makes sence.
I certainly expect PVM to be in there, I just know that it's quite a long way past my expertise atm. I imagine if I had a computer radio then I could do it there with two regular ESC, but, alas, I haven't got the money to get the Tx.
could you than just use you existing Transmitter with the computer, a few transistors here and there, and a little bit of servo/solnoid on the Tx to control analgoues?
What you want is called a mixer for either a v-tail plane or differential steering. Search either for "V-tail mixer" or "Differential steering mixer" They are also sometimes called elevon mixers. Some premade mixers: http://www.robotcombat.com/marketplace_rc-acces.html http://www.bill-tek.com/Elevon.htm http://www.hobbypeople.net/gallery/128460.asp http://www.robotlogic.com/product_imx1.html And DIY: http://www.rc-float-flying.rchomepage.com/RCWeb/PIC/Twin Power.htm
Out of interest, what's wrong with servo's? How will you be getting the accuracy you need from a normal motor instead of a stepper?
I'd like avoid [servos + variable resistors] because of the weight. (For clarity: I was refering to mechanical speed controls) Those mixers could be exactly what I need, the 'tank' one in particular. (though the two motors are fore and aft rather than left/right.) In fact, one of those would be ideal for the other half of the control system I need. Does anyone know of a good UK source for those?
I reckon you could get the parts for ~£15, not counting motors. I would get a 433mhz radio module from maplins for £10, two npn power transistors from maplins for £1 (If you need to be able to reverse, get 4 power npn and 4 power pnp), and two picaxe microcontrollers from tech-supplies.co.uk for £1.50 each. Then, you just send a signal to the radio module using one picaxe, and then the second picaxe will recieve the signal and control the motors with the two power transistors. It may soung hard, but is really easy. It would preobably take no more than an hour if you had never soldered before. The picaxe can send and recieve ir signals, so I would send these to the radio module, as ir is a built in protocol supported by the chips. I have done a similar project for a hornby train, which is controlled by the same radio module, running off fixed 12V rails. BE CAREFUL - although the radio modules are hard to destroy, I toasted one by connecting the reciever to 12V, it likes 5V like the picaxe. 5v is more than enough to switch the transistors if using even 12V, although the output would be closer to 11V.
Well that sounds rather complicated whatever you say! I might just go with normal ESCs for now, need to test my concept first anyway. BTW: I got the mixers via ebay, no problem at all.
I just want to point out that the "Tank style" and "V-Tail" mixers both do exactly the same thing, just for different applications. Post some piccys of whatever you are building! Oh, and fishcake, one of the advantages of using a R/C system is that all the electronics are built and already programmed. Also, the range is much better (rc systems can go a mile or more!)
Well I can go so far as saying that it's intended to fly, nothing more. Not just being secretive, I'm just not sure it'll fly!
