My foray into multicopters - A Hex

Started by ashok baijal, December 04, 2014, 10:50:17 AM

Previous topic - Next topic

0 Members and 2 Guests are viewing this topic.

ashok baijal

I was lucky to have won the shopping spree at RCB in the 5th Anniversary Sweepstakes. For me multicopters is a totally new field, so decided to make a purchase a hex frame, 6 motors ( Avionic C2830-850kv ), 6 ESC  (Avionic 30 amp ) and 10 * 4.5 props. I plan to use the kk board that I had purchased from a forum member. Finally, sat down to assemble it.

First doubt. While the + and x configuration are easily identifiable for a quad, which is + and which is x in case of a hex. I am attaching a drawing for two possible configs. So please help me in identifying what is figure A and what layout is figure B. Which of the two configuration is easier to fly?

SK1701

The hex looks good so far  {:)} . I don't think either configuration is easier to fly, it is just a matter of which one you prefer, which will prevent you from losing orientation.

ashok baijal

I found the answer to the layout from the kk board itself. A is a + cofiguration while B is the x configuration. Since 3 booms are white and 3 are red, the + configuration will be easier to identify while the hexacopter is in the air as 3 similar coloured arms will be facing the front and the other coloured arms will be facing the rear.

sundaram


sooraj.palakkad

Good luck, btw, which is your KK board ? KK LCD or KK5.5 ?
RC Hobbyist and an Aerial Cinematographer..

ashok baijal


sooraj.palakkad

yeah, KK2 is easy to setup and fly, I asked it because, I started my first multy with a KK5.5, but I couldn't get that board to work, it's not that easy.
but KK2, is almost plug'n play !
RC Hobbyist and an Aerial Cinematographer..

ashok baijal

Started the build. Soldered two units. By tomorrow evening hope to complete the soldering part. Hope everything goes smoothly.

sundaram

Is the Avionics ESC programmable  or with pre flashed simonK  firmware.? If programmable you need to ensure throttle ranging is done for all and all are with common option enabled. Preferable are no braking, fast start, high timing, 3.0 volt cut off, and reduce speed enabled on cut off  and not total cut out. Best is to flash all with simonK  but I am not sure if avionics compatible with simonK.

ashok baijal

I had asked the sales person to give Simon K version. But later I realised that they are normal ESCs. On going through their website I found that they stock Simon K 20amp ESCs and not the 30amp. They came without a manual, so not aware how to programme them or reflash them. Maybe forum members who have tried it can help.

sundaram

https://drive.google.com/file/d/0B4saiZvhGj-CUlhmX05MQkhKMm8/edit

Baijal Sir this should help. As I see it the default settings for ESC are good. i.e Braking disabled, Low voltage cut off soft cut off, Low voltage threshold 3.15 Volts, Startup speed Normal, Timing settings low. If you ensure all ESC are in default settings then you are good to go for now. You may need high PI gain settings with default settings and you will get less time of flight too but it should be ok to begin with.

However later you may experiment with lower cut off voltage of 2.85 volts for all ESCs for longer flight time and higher timings settings of ESC for lesser PI gain settings. But both may not be necessary at all.

ashok baijal

@Sundaram Thanks for your guidance. Going ahead with the soldering.

Where to place the battery?

sooraj.palakkad

I think you have DJI F550 frame ???
the best places for battery in this frame is either bet ween the two center plates or on the top plate. tying the battery down the frame is not good as the landing skid is of very short length.
If you plan to place battery on top plate , then KK2 board can be placed securely b/w the center plates, otherwise, battery b/w center plates and KK2 on the top plate.
RC Hobbyist and an Aerial Cinematographer..

ashok baijal

If I place the kk board between the two plates then it becomes impossible to see the lcd, though it is the best place to mount the kk board. This way all the wires would be neatly tucked inside. Any solution for the lcd?

The second alternative of placing the battery between the two plates is rather scary as the lower plate also serves as the power distribution board and soldered connections are all around. Looks like the frame is very badly designed.

SK1701

I have mounted my kk board on the top plate of my quadcopter. This allow easy access and adjustments (for PI tuning, receiver tests etc.). I mounted it in its original foam box and stuck it on the quad using double sided tape. I snaked the ESC control leads through the holes in the top plate to reach the kk board. Nice soldering of the PDB. There seems to be quite a bit of room for the battery. The soldered connections should not pose a problem. If you are concerned, you could insulate the solder joints with a few drops of hot glue.

sooraj.palakkad

don't be afraid of the soldered joints, there is nothing goihn to be short circuited unless the joints come off, .
there is also this way, you can mount both KK2 and battery on the top plate. I have once used this frame, then I put the battery b/w the plates.
RC Hobbyist and an Aerial Cinematographer..

ashok baijal

OK. I will place the KK board on top. As suggested, I will put hot glue over the connections or a layer or Araldite. Black paint might also work.

Found a good design with the battery in the lowest section keeping the CG low

sooraj.palakkad

I don't recommend battery under the bottom plate, unless you get extra tall landing skids, the landing skids on the frame are too small.
either put battery on top plate or bottom plate.
and covering the soldering is not at all necessary. still it is of no harm.
RC Hobbyist and an Aerial Cinematographer..

K K Iyer

@ashok baijal

After you complete your hex, we must compare notes.
Here is a picture of my quad (10x10cm), haha

ashok baijal

So the solution I came up with is to make a battery tray using pvc 2mm foam board and affixing it with double sided carpet tape to the lower plate. Accomodates 2 3s 2200mah batteries. Parallel harness cable will be attached to the power distribution plate.
Pictures of the arrangement attached

Why two batteries? Just because I have them and would not like to buy a fresh one now.

ashok baijal


sooraj.palakkad

Good battery compartment idea:thumbsup:
The quads like Iyer sir have cost from 1500 to 3500.
RC Hobbyist and an Aerial Cinematographer..

K K Iyer

1700 Diwali special from Hellyflier!
Even my dad was able to fly it (somewhat)
With no instruction other than throttle on left!
Ten min charge, 4 min flight, but no spare battery.

ashok baijal

Next set of questions.

1. There are two pins for connecting the battery and another two for connecting a buzzer. I think that must be for monitoring the battery voltage. Am I right?

2. In addition there are 6 (2 * 3) pins on the left side of the switches. What are they for?

3. If the battery voltage can be monitored by the KK board, how to change the cut off voltage on the ESCs to a lower setting as suggested by Mr Sundaram (Post #10 above) without a dedicated ESC programming board.

SK1701

1. Yes, one set of pins is for the buzzer. The one closer to the top of the board. the pin to the right is positive. The other pair is for monitoring the battery voltage and to this you will need to take a JST plug and solder it on to your PDB and connect it here. In this pair, the left pin is positive (I think, please check carefully)

2.These pins are for updating the board firmware by ISP (in circuit serial programming). To this, you will need an USBasp tool with a 10 to 6 pin adapter (or you could do it with an Arduino).

3.The ESC manual posted by Sundaram Sir has instructions on using your transmitter to program the ESC. Follow the instructions on the last page. This is pretty inconvenient way to go about things. Perhaps you should have got pre-programmed SimonK flashed ESCs.