I am working up to make an RC hovercraft which will be using a BLDC motor for lift system,
a brushed DC motor for propulsion system
a servo for rudder assembly.
I do not have a standard Tx Rx system(futaba or alike), so i have decided to develop a Tx Rx system which will be used to switch ON and OFF the lifting motor(BLDC motor) and wil be able to run the propulsion motor at low,med,high speeds and in reverse direction.
Also ,it will be able to control the rudder servo.
now where i am facing problem right now is the issue with BLDC motor. I want to know that can it be triggered using a 555 timer IC connected to the ESC which is further connected to the battery and BDLC motor.
If this is possible then i would like to know HOW?
A 555 ic alone can do this job ?or a microcontroller is a must?
i have attached circuits and draft build
PS.-bdlc-brushless dc motor
esc-electronic speed controller
Check this circuit:
www.rcindia.org/self-designed-diy-and-college-projects/cheap-servo-esc-driver/
It uses a 556 timer IC. You can easily drive an ESC with it.
BTW, which tx-rx ckt. are you planning to build?
Thanks for the response sir.
Well we are making a Tx Rx set analogous to fan regulator.
We are referring to the circuits attached above.
As i am new to RC stuff, i want ur guidance to proceed in correct direction.
Can the circuits i had attached be used in conjunction with the circuit u referred me to (using 556) TO CONTROL BLDC MOTOR WITH ESC?
i am relying solely on ur response so please answer carefully.(i need to develop this as my final year project and submit it within next 5-7 days )
if possible,gimme a call at 08882324282
Saurabh, it is very easy to make an hover craft.. use a plenum chamber under the craft.. use small lift fan compared to big dia, to eliminate torque reaction.. a plenum chamber will increase efficinecy to 80 % and takes less power to lift up.. you can simply use motors from CD drives instead of a brushed motor.. this helps to reduce weight to a great extent with immense power delivery.. use small fans for propultions with a kort nozzle, and add fins, on it, go with thrust vector instead of conventional rudder assy.. this gives you a very keen steering controls with accuracy.. you can also try with contra rotating props in small dia, for lift fans, gives you a very high quality controls instead of wavy own its own like responses.. making an ESC and drives are easy, but today you can buy ESCs for 450 or less Rs/- so, the time and effort is saved a lots.. for skirts, in dry situation you can use moderm umbrella cloths with silver lininng inside or can use poly flex sheets that used in bag making.. can buy in various grades.. a plenum chamber is a must, to save energy and for correct nature.. with three CD drive motors you can use two 850 mA/H batteries in to 7.2 volts, will give you a run time about 20 minutes..remember, an improper designed hover craft wastes a greater energy in vain.. and you must use a flexible skirt on it, so, it works in any surface with ease.. can also try with small BLDCs, or can also try with brushed motors.. but motors from CD drives will be amazing because of its high power delivery to weight and size..cool screammmmmmmmmm.. have some nice crafts.. :thumbsup:
making a radio set is quite easy..but i think buying a second hand radio is far better than making one.. you can rearrange the potentiometrs of the TX for a thrust control mixing, and can also use a simple Gyro, to control the lift and thrust motor variations.. this gives you a pin point accurate controls, instead of running all the way.. a suction duct will also increases the efficiency of lift fans.. you can make a big good craft from straw board, of 3mm thick ( Coro sheet).. it will be more easy to make pleanum chamber with sections.. lifts like a lift..with very less power.. a small dia 3 bladed prop will be more better.. a duct fan from a SMPS can also use for lift fans.. works great with CD drive motors..:thumbsup:
Tx- rx analogous to fan regulator?
Why don't you use a toy-car radio instead?
The best suggestion I can give you now is get a cheap airplane radio so you can easily control ESC and rudder servo. Use the brushed motor for lift and use a switch to turn it on/ off. And use the BLDC for thrust.
Swapnil sir,i saw ur 556 ic based circuit and i must say that u did a great job.
Now my concern is :
1. can an ESC and a SERVO both be controlled by the single circuit simultaneously?
2. is it necessary that the ESC should be of BLDC motor only and cannot be an ESC of BRUSHED motor?
3. what are the pros and cons of contra rotating props and should i consider them to be used in our project?
4. i have 3 batteries (cellphone) of 950,1300 ,1350 mAh respectively.can i use them in series to power the entire apparatus on craft?
We r running out of time,it would be great if u can respond quickly.:-)
i donot have a toy car now.
How can i use that toy car radio btw?
I mean if i buy a new toy car,what will i be able to do with the Tx Rx set of it?
(considering that the RC toy car can move in forward and backward direction plus LEFT and RIGHT motion)
also,i wanna clear myself on it: how many channels are said to be there in this RC car? 4 or 2? i oftn get confused with this.:-)
1) An ESC and servo can be given a common signal but then you won't be able to control them independently.
2) BLDC ESCs are completely different from brushed ESCs. They have FET pairs that are switched on at a phase difference. Brushed ESCs simply won't work.
(And you must have noticed that BLDCs have 3 wires and brushed ESCs have 2, so...)
3) I've used them in HoverBot v2. They work good.
4) The mAh rating just shows stored charge density and not the max current batteries can supply. Cellphone batteries don't have high 'C' rating as high current isn't required. As such, they can't be used for powering your motors. (Search what LiPo 'C' rating means and you'll understand)
Toy car radios can be used if you can interface their receivers with a micro-controller. Otherwise it'll be difficult.
thank u swapnil sir.
I hav one more question to ask. can i use a brushed motor and a brushed motor ESC with the 556 based circuit u recommended?
Also, can u provide me the other side(bottom) of the 556 based circuit?please
Yes, you can certainly use the servo driver circuit for a brushed ESC that works on servo signals.
The bottom of the circuit is just tracks, no components are there. The circuit diagram (first pic) is very simple. If you have any questions regarding that, please ask.
ok...
Q1.what are j1 n j2 used for?,if they are not sorted to j1 n j2 respectively??
They are simple jumpers. Pin 2 goes to pin 6 and 5 goes to 8.
can this circuit be used to control one ESC and one SERVO simultaneously?
If yes then how?
Also ,i would like to know what wud happen if we use same kind of capacitors used in the circuit(paper capacitor for example).
And one more thing ,the circuit diagram has got 2 POTS but u have used only one pot in the designed pcb.WHY? moreover, one resistor is also missing(i m not sure which one)...
I wil apreciate if u can give us the back side of the pcb so that we can get a better idea of components placement.
No, you'll need two seperate circuits for servo and ESC.
The 2nd pot isn't soldered. It goes into the male header pins at the right side.
I dismantled that PCB long ago. If you follow the circuit as it is, there should be no problems.
Thank u sir.
But it seems dat u missed my query regarding CAPACITORS...:-)
Thats because I didn't clearly understand your query.
HELLO VC sir n SWAPNIL sir!
I have 7 more days to complete the hovercraft.
As we are lacking time and money and EXPERTISE i thought to work up on the design considerations.
I thought to make up a hole at 30-40 degrees from horizontal and extend it through a duct like structure with a conical ending(nozzle like structure)..
I think that upon switching the lift motor,it will generate too much of thrust(as you suggested me VC sir,in case i go with BLDC 2822 motor)....
So in essence ,we will use some part of the lifting pressure/thrust to provide the craft linear motion.
We may use a LID (optional) for hovering at a place.
wat do u suggest VC sir?I need ur EXPERT advice once again.:-)
Sketches linked- https://picasaweb.google.com/111375374001884649365/HovercraftNewDesign
ok....well my question is that IS IT NECESSARY TO USE DIFFERENT TYPES(paper cap,electrolytic cap and ceramic cap) OF CAPACITORS IN THE CIRCUIT?
what wud happen if we use all the capacitors of same kind(say paper capacitor for example).
It's not necessary. Back then, I just used whichever gave best results.
PLEASE COMMENT ON THIS DESIGN.:-)
https://picasaweb.google.com/111375374001884649365/HovercraftNewDesign
I checked out your designs and here's what I think.
1) The thrust nozzle will act as a pressure outlet and will shift CG resulting in lower efficiency and imbalance.
2) It won't give good enough thrust to overcome inertia.
There will be a slight tendency to rotate because of lift motor torque at full throttle. Better take that into consideration.
A non-circular duct (as in 1st pic) is inefficient (gives much less lift) due to leakage at corners. Consider changing that as well.
What if i make piping on both the left n right boundaries of the hull.
Cylindrical structure ,without nozzle, one on the extreme left and other on the extreme right ?
U think it will work?
Why don't you give it a try? If it doesn't work you can try other methods.
swapnil sir.,i have designed ur 556 based circuit but its not able to generate required delay.
I tested it with a servo....can u please assist me here?
Do you have access to a digital oscilloscope or PC oscilloscope? It will make testing/ debugging easier.
Google 'free PC oscilloscope' if you don't want to do this in a college lab.
We'll need to check specific points on the PCB circuit. Firstly, could you post pics (track side and component side) of the circuit you made?
Your new design seems promising. Give it a try, it should work. However, I feel that you are needlessly complicating the issue. As per my conversation with you, you just have to show that the concept works practically. All these complicated 'parallelepiped exhausts and oscilloscopes' are freaking me out. I feel my advice is woefully inadequate here. Just follow your heart and build it. STOP, PLEASE STOP being so theory bound. For heaven's sake - Just do it!
Single motor + fan is enough to create sufficient lift and thrust for a 18" Hovercraft. I have done it with a larger model. No complicated calculations or electronics involved. Remember what we talked about. If an idiot like me can do it, so can you. All the best.
http://www.rcindia.org/boats/scratch-built-hovercraft/
Alas, it's a college project VC sir, that too for electronics branch. Unless you show them (lecturers) some circuits and complexity, they'll term it as a 'toy'.
I saw a group's project being ridiculed because 'it was made by connecting modules, which anyone could do'. The modules they were reffering to were rc electronics...
I understand Swapnil. That is the pity. Let's help Saurabh to supply as much theory is required so that his professors go into a coma deciphering them! :giggle:
Frustrating Indian Education System @ 2012. :banghead:
O you are so humorous VC sir.I do get your point that it should be simple,neat n clean ,the probability of success will then be close to 1.:-)
Swapnil sir,i m posting the link to pics...now what i want from you is to please tell me that 2millisecond pulse means what?
a-the amplitude is 1 for the duration of 2 milliseconds(if this is correct then what should be the OFF time duration?)
or
b-the complete cycle completes in 2 milliseconds(meaning 1(high)for 1ms and 0(low) for 1ms)
Also, i would like to know that if a circuit is capable of generating 0.5,1,1.5,2 ms pulses (one at a time of course), will the signal(output or generated pulse train) be able to run an ESC or SERVO at different speeds?(just for confirmation)
https://picasaweb.google.com/lh/photo/or4ftsjYnHh3Er8Ju_cBualVV2ZSTrSaGncxjV7WC7c?feat=directlink
https://picasaweb.google.com/111375374001884649365/April82012
The pulse width (on time) must be between 1 to 2 ms. The time period per cycle must be 20 ms (that is frquency of 50 Hz). Pulse amplitude must be 5 Volts.
I'll check your pics after 6 AM. :)
O.K, checked the pics...
1) Why have you used a 50K pot instead of 10K for R4?
2) Do not vary R4 and R5 (in your circuit) simultaneously. R4 is for varying pulse-width and R5 is for frequency adjustment.
3) C1 (100nF) connects to pin 13 and not the junction of R1 and R4.
Make the corrections, run the simulator and post a complete picture of the oscilloscope. Use screen capture instead of camera for better resolution...
Never use 12V for a servo circuit (like you did in the 555 simulation). Always keep Vcc between 4.8V & 6V (5V best).
You should have tried the circuit on a breadboard first...
Some points regarding PCB:
1) Never keep component pins (legs) long. Circuit will be susceptible to noise (particularly this circuit).
2) Solder one end of the capacitor pin as close to the IC pin as possible.
Waiting for the corrected circuit and oscilloscope pics...
In the circuit i have used 10k pot only...(2k pot is absent as you also didnt use 2k pot in ur circuit.)
When i tried to use the circuit to control servo,i failed(but some vibrations and some heating effect was there in the servo- what does that mean?)
In the simulation circuit, i observed that pulse width was not varying with pot adjustment so i tried using 20k n 50k pot.
But now after following ur guidelines, i can see that the pulse width is 2ms and cycle is of 20ms(please to see that).
And,as i remove the connection between the 2k pot key and 10k pot key,i observe that the pulse width remains unchanged(2ms) in spite of varying the pot(0% through 100%).
i am using someone else's computer(no screen capture software installed in this machine), so am bound to rely on camera only.:-)
here is the link to today's pics.
https://plus.google.com/photos/111375374001884649365/albums/5710132455154914689?banner=pwa&authkey=CMuOnajxqdUb
(last ones),Is there any way to obtain desired results without using 2k pot?
Quote from: saurabhreigns on April 08, 2012, 01:45:24 PM
In the circuit i have used 10k pot only...(2k pot is absent as you also didnt use 2k pot in ur circuit.)
I most certainly have used the 2K pot! It's the small trimmer-pot just above the 556!
Quote from: saurabhreigns on April 08, 2012, 01:45:24 PM
...some vibrations and some heating effect was there in the servo- what does that mean?
That means your servo's fried or in a bad state. You shouldn't have tried it before getting simulation results. If the servo still works without jitter or heating-up don't use it till you get perfect servo signals.
Quote from: saurabhreigns on April 08, 2012, 01:45:24 PM
...And,as i remove the connection between the 2k pot key and 10k pot key,i observe that the pulse width remains unchanged(2ms) in spite of varying the pot(0% through 100%).
The 10K pot is the only one that controls the pulse width (and hence the servo position).
Quote from: saurabhreigns on April 08, 2012, 01:45:24 PM
i am using someone else's computer(no screen capture software installed in this machine), so am bound to rely on camera only.:-)
Is there any way to obtain desired results without using 2k pot?
You don't need a screen capture software! Just press the [Prt Scr] key beside the F12 key and paste (ctrl+v) in paint or irfan view. :)
The 2K pot is used to get the correct frequency (50 Hz) without which a servo won't work!
The pulse width should vary between 1 and 2 ms only. Beyond those limits your servo might get fried again!
i tried hard but failed to locate the 2k pot on ur circuit board.
where is it?
Hmm... maybe you haven't seen a trimpot before.
Here it is.
If this is 2k pot then where is the 10k pot sir?
i mistook this pot as 10k pot.:-)
The 10K pot, was kept detachable in my circuit. In the above pic there is a pair of male header pins right above the power connector. The 10K pot goes there.
ok....now i got the chunk.:p...thank u sir...i will troubleshoot the ckt tomorrow i guess
{:)} {:)} {:)}
no fruitful results obtained even after troubleshooting the circuit which,at the end was succeeded to produce 2ms on time with 20ms cycle duration.
Now we are using arduino board for BLDC and Servo control, in conjunction with an IR remote.
Vivek Kumar Singh(rcelectro.com) is helping us a lot.:-)
Oh, he has helped me too! Awesome guy!
You'll surely succeed now! Do keep telling us how it goes.
surely.
acha sir,tel me this.
regarding the design of the craft,tell me which would be better?drilling hole through the hull at 90 degree or at 35-45 degrees(as depicted in sketches i had shown you)
Depends on whether you want to use a single powerful motor for both thrust and lift or separate motors.
I remember a build-thread on RCGroups that started with a single motor design but ended up with separate motors as the single motor design didn't give good-enough speed.
But, you have to demonstrate it indoors, so I guess single motor design should be okay.
We will certainly stick ourselves to single motor design.
Speed is not a requirement ,WORKING is all we will be required to demonstrate..
Now tell me which way should i drill the hole (for thrust)
I have changed the skirt now with the parachute fabric as you suggested VC sir.i am going to use Emax2822 BLDC motor with a 6x3 prop(available).
I want you to guide me if it will work or not coz vivek sir said me today "i dont think it will ever work".
what modifications should i do to make it work if he is thinking right!??https://picasaweb.google.com/111375374001884649365/DropBox?authkey=Gv1sRgCMuOnajxqdUb#5731221990305930946
No I don't think this open skirt will work. The skirt has to be a sealed chamber. Follow this link:
http://www.model-hovercraft.com/2000tdx/2000tdxskirtplan1.html
after a hell lot of time and efforts and ups and downs ,,,we are now done with succesful test HOVER of our hovercraft.
video link(please see and comment/leave feedback/ suggestions in the comments section)-
http://www.youtube.com/watch?v=Clx1Q4pgplI&feature=youtu.be
image links-
https://picasaweb.google.com/111375374001884649365/DropBox?authkey=Gv1sRgCMuOnajxqdUb#5739455422219636114
https://picasaweb.google.com/111375374001884649365/DropBox?authkey=Gv1sRgCMuOnajxqdUb#5739455490139196002...
VC sir, please give some feedback,we have used the nitrile pipe for the skirt however the parachute skirt(the silver one) was also doing job(obviously,there were balancing issues as it was a draft and rough one):)
toy motor i have .
https://picasaweb.google.com/111375374001884649365/DropBox?authkey=Gv1sRgCMuOnajxqdUb#5739471858400084786
https://picasaweb.google.com/111375374001884649365/DropBox?authkey=Gv1sRgCMuOnajxqdUb#5739474630405488162.
the dome structure with holes.
What if we go for a cylindrical or circular plate like structure?or a cuboid kind of structure in place of dome?
Dome structure looks OK, you will need more / bigger holes.
Motor is too small, you need something bigger. Will try and upload a picture.
ok i am waiting.;)
FINALLY<AFTER A SERIES OF FAILED ATTEMPTS AND TOO MUCH PAIN,i did it....it took me two long months although....(i am a beginner after all..:-P)
I made it using:
1 arduino-uno development board
2 a brushed DC motor and IC-L293D
3 A brushless motor EMAX 2822
4 A plastic geared 9gm servo motor
5 A Lithium Polymer battery pack- 3cell,20-30c,2200 mAh
6 And an ESC for brushless motor
7 two propellers ,6x3 for lifting fan and other 8x4(not sure) for thrust(linear motion)
thank u VC sir,swapnil sir,vivek sir,and roopeshkrishna sir for ur valuable suggestions and advice.m really thankful to u all.
here are the links to project's final appearance,https://picasaweb.google.com/lh/photo/5vXEkwwSEX-Io-URl3hWNqlVV2ZSTrSaGncxjV7WC7c?feat=directlink
presentation and report that i had to make as per curriculum http://www.scribd.com/doc/95579554/Amphibious-Surveillance-Hovercraft-Major-Project-Final-Year-Btech-EC-2011-12
http://www.scribd.com/doc/95579232/Amphibious-Surveillance-Hovercraft-Major-Project-Final-Year-Btech-EC-2011-12....
PROGRAM CODE IS ALSO GIVEN THERE....SO,if any beginner requires,he/she may refer to it.:-)
Congratulations!
Now I am looking forward to your second build.No calculations, no theory - just take your time and ENJOY yourself. PURE FUN!!!