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[project] Racing Wheel FPV

#1 User is offline   aotsukisho 

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Posted 16 May 2011 - 04:42 PM

Because ERBE and O-Revo are near completion (and two bitch ass ebay sellers decided to use freight shipping on stuff I ordered) I decided to start a new project. This will be a FPV (first-person view) project, using the MadCatz wheel to interface with the radio system. I've gotten some progress by tearing apart the wheel and I am 100% confident that it will work with our Hitec Laser 4 FM radio.

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pulling apart the MadCatz pedals

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the pedal weight is actually concrete

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brake and throttle pots

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all three pots in this wheel are 6k units

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pulling apart the Hitec Laser 4

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reference photo for the connectors

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brain board removed

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reference photo for the channel reverse switches

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pulling apart the MadCatz wheel

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steering pot setup

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testing with a servo plug attached

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Hitec transmitter has Channel 25 crystal installed

What this project needs (aka wishlist from Changland):
- 5.8g 200mw FPV Wireless AV Tx & Rx Set
- 1/3-inch SONY CCD Video Camera (PAL)
- Turnigy BASIC FPV Goggles 428 x 240 Wide Screen (if I feel like a bamf)
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#2 User is offline   aotsukisho 

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Posted 17 May 2011 - 03:55 PM

guess what I just bought...
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#3 User is offline   aotsukisho 

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Posted 18 May 2011 - 05:31 PM

Another candidate for AV radio:
http://www.dpcav.com...&cat=278&page=1
http://www.dpcav.com...&cat=278&page=1

or this one too:
http://hobbywireless...products_id=404
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#4 User is offline   aotsukisho 

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Posted 23 May 2011 - 05:05 PM

well, a toy came in today.

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hard case

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the guts

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charging up the Myvu Crystal pendant.
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#5 User is offline   aotsukisho 

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Posted 26 May 2011 - 04:23 PM

no real progress, but parts did come in the mail today. Just dumping links for now.

http://arduino.cc/en/Main/Buy
http://arduino.cc/en/Main/Hardware
http://www.sparkfun.com/tutorials/148
http://www.rcgroups....ad.php?t=942699
http://www.rcgroups....ad.php?t=964184

http://www.sunsky-on...transmitter.htm
http://www.bestoffer...bo-p-15758.html
http://rcexplorer.se...14/FPV/FPV.html

http://shop.modernde...roducts/bbb-kit
http://shop.modernde...products/bub_ii

http://www.arduino.c...?num=1288247961
http://www.starlino....elerometer.html

http://www.rangevide...products_id=217
http://www.rangevide...products_id=213
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#6 User is offline   aotsukisho 

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Posted 31 May 2011 - 12:48 PM

had a productive weekend.

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preparing a pcb for the 3.5mm audio jack

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all pins fit through

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pins bent for better contact

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and soldered

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removing the original harness

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mockup of the mounting solution I came up with, using extra E-Revo battery spacers

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screw spacing for the original memory card slot mount

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screw spacing I needed for the pcb

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drilling the battery spacers

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wire work

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mounted to the battery spacers

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had to nibble some of the pcb away due to the plug's diameter.

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mounted up using M3x10mm countersunk screws on both ends

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external view

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cable plugged in

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putting the wheel back together

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closeup of the steering pot

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I used a lot of wire to give myself physical leeway, so I needed to think of a creative un-tangling solution

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reassembled!

Next is the pedals, which is harder considering there are six contacts I need to access. I'm thinking of using standard Ethernet hardware, and replacing the Serial (?) cable it currently uses.
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#7 User is offline   aotsukisho 

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Posted 06 June 2011 - 04:37 PM

http://www.avsforum....d.php?t=1331583
a cool guy found a possible fix for the Myvu Crystal washout problem I've been having.
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#8 User is offline   aotsukisho 

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Posted 17 October 2011 - 11:41 AM

made a camera pan using a servo horn and the extra Traxxas servo I have laying around. check it out!

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mounts the Turnigy micro camera

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used extra Revo caster clips as spacers so the camera mount wouldn't hit the servo screw

took a video as well, sorry about the misfocused camera.


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#9 User is offline   aotsukisho 

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Posted 09 November 2011 - 04:23 PM

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the AV radio from China came in recently

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unboxing

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they look pretty nice, casing is identical except for 'transmitter' and 'receiver' stamped on

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looking at the business end.

I don't know if I'm gonna be taking them apart for use in the system, but I do want to test them out before I go any further. Sometime this weekend perhaps?
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#10 User is offline   aotsukisho 

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Posted 16 November 2011 - 04:20 PM

did some static range testing today during my lunch break. some shots through a video camera (normal camera pointed at TV) at varying distances, through varying amounts of walls.

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Test 1: Direct connection
hooked up the camcorder straight to the TV. Zero interference, which is expected.

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Test 2: Wireless connection (close); 0 feet, 0 walls
hooked up the AV stuff to the radio, and it works just fine.

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pointing the camcorder at the AV radio layout for Test 2

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when the receiver is powered on but the transmitter is off our out of range, you get loud static.

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Test 3: Wireless connection (mid); 20 feet, 2 walls
putting Nemuri Pikachu in our parlor. some fuzziness going on.

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Test 4.1: Wireless connection (far); 40 feet, 5 walls
I put the transmitter in my bedroom on the ground, and got no reception.

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Test 4.2: Wireless connection (far); 40 feet, 5 walls
I then tried putting the transmitter on the bed (three feet off the ground), and got signal. It would cut out now and again and has heavy interference but I think it's not bad failure mode. Progressively gets worse when the signal gets weaker.

Verdict: I think it's safe to use. I don't plan on using this setup indoors, but even if I do I can rest easy knowing I can traverse 80% of my house without losing AV signal. Both ends of the radio operate at 5v, which makes things extremely easy from the vehicle's standpoint. I ordered a pocket oscilloscope to measure how much Vripple the included AC adapters have, and whether or not the Hobbyking UBECs are within spec or if I have to buy a 'real' (Castle) one. These things come with a sturdy casing, power button/LED, four channels and run at 5v? I just hope they are up to the task of vibration/movement, because then they will be perfect for my application. I think I will make an effort to vibration-damp the mounting, since this did cost me $50.

edit: bonus shot

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one of my dog sleeping outside, 20 feet away through a wall and the dog kennel (chainlink fence).
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#11 User is offline   aotsukisho 

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Posted 25 November 2011 - 01:19 PM

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pulling apart the transmitter

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a QC (warranty) sticker over a screw

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opening it up

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the front of the module is IR tinted plastic

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quality soldering...

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put on a servo power lead for the BEC, and hotglued both the wire and the 2.4GHz module

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the connections on the underside of the board, to bridge power from the transmitter half to (what I assume to be) the missing IR control half.

I was changing out the wheel-pedal connection from a serial type to standard non-crossover RJ45 connections.

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the connection on the wheel's PCB

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the throttle pot in the pedals

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brake pot

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dremeling the wire exit on the pedals for an RJ45 jack to fit

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success!

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soldered connections from the jack to the other electronics

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wheel connector, hotglued in place

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pedals connector, hotglued in place

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haven't tested it on an Xbox yet, but the connections are the same tested with a multimeter

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all put back together! now to just design the PCB for the FPV ground station.
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#12 User is offline   aotsukisho 

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Posted 28 November 2011 - 11:47 AM

got a lot done this long weekend. In fact, this project is 99% complete. Here's a log of what I did on Thanksgiving night/Black Friday morning

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designing a circuit that will allow me to run the brushed motor on 6s with a 3s max ESC

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after I proved that the circuit worked properly, I built it on a PCB and here is the final output being tested (on 9v)

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building a mount for the wireless AV transmitter

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this will fit into the keyed bottom

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like so

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mount is....mounted

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WAV bolted to the rear body posts

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a view after it's mounted

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looking from the top this time

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making a metal bracket for the camera mount

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bolt for the universal joint

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mounted to the front shock tower

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camera mounted

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looking from the front

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weight distribution will sadly not be even, I will probably need to use 550 brushless motor and heavier ESC for it to even be close

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closeup of the ESC 2nd stage board

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testing my ESC setup at 6s in the truck, with the 550 Mabuchi brushed motor installed

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pulled this at a brake-induced full throttle stall, looks like if the motor is geared correctly it will handle the full 10A of current.

The mosfets I used in the 2nd stage board (BUK453-50B) are rated to [email protected] and I have two of them in parallel, so I was wondering why they were getting hot. Looking back at my circuit design I could not find anything wrong with it, but then I remembered what RCers had to do in the 'olden days'...motor caps and Schottky diodes. Fortunately I had some spares of both; a MBR2545CTG Schottky (30A, 45v) and some 220nF ceramic caps will have to do.

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the Schottky diode mounted on the motor. Yay for TO-220 package!

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mosfets now run cold. hooray!

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final testing for the night, status LED on the board mimics the motor

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final test: motor running. success!

Now, for the work I did yesterday (Sunday). The electronics on the truck itself was complete, all I needed to do was to build the radio/wheel interface. Unfortunately, I found out early in the day that my Hitec Laser 4 had died for unknown reasons, and I needed to use a different radio. Fortunately, I had just the thing, in the form of my Turnigy 9x. There are six usable channels on this radio for my purposes, 4 of them proportional (the sticks) and two of them toggle (landing gear, throttle cut). I decided to use this radio for the project, as I think it will be fun controlling both Fancar v2.1 and Fanboat with a wheel.

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pulling apart the 9x for the first time

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measuring the pot resistance. thank you to whomever decided that 600Ω pots are the way to go with everything

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closeup of the throttle side stick

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closeup of the elevator stick

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the 9x uses a 3.5mm trainer jack, which is perfect since that's what I'm using for the steering wheel hookup.

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bending the pins on my ethernet jack to solder on the pot connections

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soldered on

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the wire unfortunately goes through the stick plastic, I would have to desolder the wires to take it out. Never mind.

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tried hooking up the steering wheel wire straight to the trainer port with the pins disconnected, but there must be other internal connections because it did not work and if you turn hard right the transmitter shuts off. My guess was that power was also being transmitted in there.

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I desoldered the plug and attached my own internally with hotglue. Isolated connections were made, and a hole was drilled for the ethernet cable to escape.

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and we have genesis! a photo of my first FPV drive setup. not pictured: millions of wires worth of the WAV system with the Myvu Crystal.

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the Revo, outfitted and ready for action.

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closeup of the motor control PCB, with a GSR sticker of course.
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#13 User is offline   aotsukisho 

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Posted 28 November 2011 - 04:09 PM

More on the motor control circuit...in the last photo in the previous post the large 1/2W resistor is 220Ω to bleed off gate capacitance, the two TO-220 packages are the two mosfets in parallel. The ESC output is on the left side of the PCB, and the right side goes to the motor/battery. Here's a schematic:

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Basically, the output of the ESC is used to trigger my own mosfets (BUK453-50B) that are rated for [email protected], which means I can reliably run a 30A motor at 10s lipo. The diode is a Schottky that I added after noticing that my mosfets got quite hot under use despite the motor drawing an average of 2A.

The ESC output and the high voltage battery output don't actually meet each other, they are isolated by the mosfets. That's why this circuit works, and can use an ESC output of 7.4v with a 6s battery (or up to 45v) and motor.

This circuit should be good to ESC PWM frequencies up to 4MHz, according to the mosfet datasheet.



The reason why the circuit is so simple is because there is NO electronic motor braking and NO motor reversing. The Revo's brake is still there on the transmission output, and the reverse gears/servo were put back in. Drive frequency and exponential curve are all controlled by the ESC. All this circuit does is allow a separate voltage source drive the motor.

The brushed ESC could actually be of any shape/size, the current rating literally does not matter. The only current it eats is whatever goes through the resistor network/LED. My particular choice of components resulted in a consumption of [email protected], my guess is roughly half of the current through both the resistors and LED. The Turnigy one I used was just the cheapest, and I had a couple of them laying around. I'm not sure if the brake function makes a difference, but I turned it off on mine. The lipo cutoff feature is handy too.
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#14 User is offline   aotsukisho 

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Posted 30 December 2011 - 11:09 AM

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Finally got around to making the ESC harness, so that the ESC's 5v linear BEC can power the AV transmitter with better ripple than the switching BEC. The UBEC will be on 6v mode for better servo strength.

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installed. The most obvious segment is the one that goes back to the AVTx.
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