20 January, 2018 at 15:08 #40726
Details left to do and wait for the bf3.2 for my board (there are no hex for BFF4 so far not even in the 0.7 beta :(. ) ? got some upgrades still to do but they are not released yet ?
RcExplorer Mini Tricopter frame (without fc and pdb)
BetaFlight F4 fc
Aikon AK32 35A esc
BlueBird Titan servo
HobbyWing 2405/2200kv motors
Hq 6×4.5×3 props
Foxeer Monster V2 with 1.8lens
Custom 3D printed mount for camera from Carbix.se
Rush 1.1 v1.4 25-600 vtx
Rx for Turnigy evolution
All graded up to 6s acc.
(To this an carbon upgrade is in progress for a stiffer cage, and a possible air soft turret was under the frame for some fun)
(Next upgrade that’s not released today is an Foxeer AIO unit, fpv cam and hd video. Should come during spring-18)
Big thanx to David, for all support the last years
Attachments:20 January, 2018 at 16:30 #40729
One thing that comes to mind is Ferrite-Cores.
Reason I bring this up is that aparently these are often used by the “fixed-wing” guys to help sort out control surface wag / jitter thats are common with Digital Servos. The theory goes that as a Servos draws current, it creates interference causing it to spaz-out. In a sense, it’s like the Servo is feeding on its’s own interference. (Or that of nearby transmitter such as FPV or Telemetry)
There are several low-cost, light-weight cores that are basicly “snap-on” over the Servo cable. Not sure why these aren’t being used on Tricopters but from what I understand, the problem and possible solution is the same for both platforms. Such as these cores shown below…
Oh before I forget…
Look up the Servo you have at the MFR website for the correct servo PWM Frequency and Center-Position. For instance, the BMS-210DMH Servo (Same one David offers) has a PWR Frequency of 240Hz and a Center-Position of 1520us instead of 1500us. Knowing this can help you provide the correct settings for the Tricopter within Betaflight. (CLI “servo_pwm_rate” & “servo_center_pulse”) Odds are good that your Servo is using a PWM of 333 Hz with a Center-Position of 1520us. Please do check the Servo tab on Betaflight and ensure that the starting center is also what your “servo_center_pulse” is set to. After the Tail-Tune the Servo tab will be updated ( naturally ) as your providing an offset based on the mechanical differance vs what the electrical properties should be.
Also, the first time you power up your Servo, do so without it connected to anything (Betaflight settings already loaded with corret PWM and Center Position). This will allow it to self-center so then you can later attach the tail mount (level) at it’s known center position. Afterwards Tail-Tune, Fly and Auto-Tune it as normal. This will help ensure that you don’t acidently hit the servo End of Limits (EoL) and burn out a motor.
Note: I’ve lost three Servos thus far, two where from EoL and one was from impact.
Kevin20 January, 2018 at 17:13 #40730
That was a smart solution 🙂 pity my cables are cut as short as possible, but if I get to much noice from my servo that could solv it.
My babytri got some noice but it goes away fast, have not put BF3.2 on that either so far (HW F4 fc on that)
Could setup an basic bf but with an baby daughter in the house I don’t have the time so I just have to wait for the hex file to my boards.
Have used 10 servos the last 2 years on my tricopters so know to well 😛20 January, 2018 at 17:25 #40731
You could also swap the cables out for shielded. I’ve seen several types with 4-wires that are of differing AWG (gauge / thickness. lower AWG is thicker).
Example: 18 AWG (power & ground for esc’s) with 22 AWG (signal for esc’s) all held within the same shielded cable.
While this would add to the weight maybe 1-2 grams per ESC or Servo cable, it would be worth it to have a completely noise free setup. (I figure it would add 5-10 grams to one of my birds)20 January, 2018 at 17:30 #40732
Thats also an thought, im an electrician so got a lot of cables at work, think I got some high end signal wires in my garage also. might swap things out if I get to much noice on maiden. Time will tell.
first of now is to get it started as soon the hex file for BFF4 is ready 🙂20 January, 2018 at 17:36 #40733
I’m an old Navy Calibrations Tech…
Did a ton of field repair on old UHF / VHF radios, Nav, Radar, IFF, Tacan and test instrumentation. Retired out after my 20 but i still got the known how.
However applying it to copters is a bit different as what we have is around 1 kilo max, where some of the systems I’ve worked on require a forklift, a laptop and alot of coffee.20 January, 2018 at 18:05 #40734
I got 3year at electronic school and 2 years as an repairman on satellite phones for Ericsson so got an idea of what you are after in the wiring, its logic so ill look into it and maybe switch some out on the mini.
Ill take it into consideration when I start my next build to, going for an custom V4 also during spring.
What servo (digital) would you say I should look into? Have bought davids bluebird up to now because its easy and they work nice on is tries.20 January, 2018 at 19:08 #40735
From what I’ve read, the BMS-385DMAX digital Servo (Bluebird) is a great substitute for David’s BMS-210DMH. It’s a bit lighter, has metal gears, has more torque but lacks the feedback wire of the 210. If your not shy about cracking it open, you should be able to wire up your own feedback system. Otherwise, stick with Davids offering just to ensure your using something thats proven.
Note: Hobbyking has it in stock.
BTW: I took a look around my house and found an old Microsoft laser Mouse that had a ferrite core around it’s USB end. I cut it off and for all intensive purposes, it would 100% work for our Servo needs. The core weights 2.2 Grams and the servo cable would easily slide throught it. (still snug though) Further more, the 2 meter mouse wire, has four 22 AWG wires (red, black, green, white) that are shielded! Quality stuff!
will post a pic later.
Kevin20 January, 2018 at 19:11 #40736
Thats awsome, think I got some old here to 🙂 smart idea
open things up is half the fun 😛 so that type could be good, ill look at it later when my daughter is in bed.21 January, 2018 at 00:55 #40741
Ok, i just put the core on, didn’t loop the wire around as its too short to do so. So far i dont see a noticeable change in the jitter. (maybe more turns would help?) Will have to wait a few days to be able to test fly it as the weather is pretty bad.
Beyond this i’ve pulled a data log of just the servo when the arm switch is active. Motors dont spin-up unless throttled so its just the Servo twitching away. (Had the FPV gear disabled but telemetry is part of the receiver card so i cant disable this.21 January, 2018 at 02:09 #40742
Here is another idea… http://www.store.revolectrix.com/Products/Accessories/Advanced-Servo-Buffer21 January, 2018 at 02:27 #40743
Here is what my servo jitter looks like with the copter armed but motors not spun-up.
Kinda looks as if the servo is overshooting and correcting, over and over again. I’ll try using a Yaw filter @ 20hz. Log file is attached to this post.
Attachments:21 January, 2018 at 12:23 #40747
Just tested to boot up my bff4 fc, all is working but need to rearrange all channels if I should run stock Betaflight software. but at least ive tested so all is working 🙂 hopefully a hex file with Triflight is in the making for my card because I really don’t have the time do edit all by myself in Betaflight 🙁
going out to the workshop tho for an customisation on the booms, need 2-3mm mor clearance so I don’t damage the fc21 January, 2018 at 13:07 #40748
Thats more like it, a small mod/cutout on the booms and they are foldable again 🙂 I missed about 2mm before so they didn’t clear the BFF4 fc, but a small cut on the backside of the booms solved this problem..
so back to the Mac for some more software checks.
Attachments:21 January, 2018 at 20:59 #40755
Kevin_erik. I found some hobby wing ubec 5-6v on bg with that core ring, need the 6v Bec so ordered some so I could filter the servo also. should be fairly simple to attach and with that Bec I get longer cables for my servo so I could put all on.
Another thought to filter the servo, 470uf cap? hot glue it on the back of the servo and solder it direct on +- should give an secure power and take away some noice
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