Nimbus Tricopter VTOL

adding one minicamera with pan tilt in nose and a second camera = 4500-4600 gr

Now the question is what will be the performance of a Sunnysky X5208 KV330 or T-Motor MN5208…

anyway the flight Q should not be more than 10 seconds before the transition

I was going through some setup parameters and noticed that Graham had this:

AHRS_EKF_TYPE = 2

and I had this:

AHRS_EKF_TYPE = 3

This controls which NavEKF Kalman filter version is used for attitude and position estimation. Is there a difference?

I found this: https://github.com/ArduPilot/ardupilot/pull/5336 which explains a bit. I also compared your params to mine and there are quite a number of differences, some of which I presume, differ due to Foxtech’s testing and development phase.

Would love to know the reasons behind some of the changes.

Good link, thanks, Graham!

I have just compared the differences between our param files. Here are the critical ones below. Since you have flown yours, all the non-Q PIDs from yours should be used. I also need to enable the weathervane features, etc. I would still love to see a V2 .param file to see what the wind resistance changes were.

Differences from Graham’s PIDs

AHRS_EKF_TYPE,2
ARSPD_FBW_MAX,18
ARSPD_FBW_MIN,11

LAND_DISARMDELAY,10

LIM_PITCH_MAX,2000
LIM_PITCH_MIN,-1500
LIM_ROLL_CD,4500

MIXING_GAIN,0.5

MNT_RC_IN_TILT,0

PTCH2SRV_D,0.04
PTCH2SRV_FF,0.4
PTCH2SRV_I,0.15
PTCH2SRV_IMAX,3000
PTCH2SRV_P,0.7
PTCH2SRV_RLL,1.15

Q_ANGLE_MAX,3000

Q_ASSIST_ANGLE,30
Q_ASSIST_SPEED,0

Q_TILT_MAX,60
Q_TILT_RATE_DN,50
Q_TILT_RATE_UP,200
Q_TILT_TYPE,2
Q_TILT_YAW_ANGLE,13

Q_TRAN_PIT_MAX,10
Q_TRANS_DECEL,2
Q_TRANSITION_MS,3000

Q_VFWD_GAIN,0.05

Q_WP_RADIUS,500 (now 200, use 400?)

Q_WVANE_GAIN,0.2
Q_WVANE_MINROLL,2

RLL2SRV_D,0.1
RLL2SRV_FF,0.4
RLL2SRV_I,0.2
RLL2SRV_IMAX,3000
RLL2SRV_P,1
RLL2SRV_RMAX,0

WP_LOITER_RAD,80

WP_MAX_RADIUS,0
WP_RADIUS,10

YAW2SRV_DAMP,0.08
YAW2SRV_IMAX,3000
YAW2SRV_INT,0.3
YAW2SRV_RLL,0.8
YAW2SRV_SLIP,0

My changes in bold (corrections/suggestions welcome):

AHRS_EKF_TYPE,2
ARSPD_FBW_MAX,18 - (good max speed for this type/size of plane)
ARSPD_FBW_MIN,11 - (Just above the stall speed of 10m/s)
LIM_PITCH_MAX,2000 - (no need to pitch up more than 20°)
LIM_PITCH_MIN,-1500 - (no need to pitch down more than 15°)
LIM_ROLL_CD,4500 - (Limits bank angle for heavy plane)

MIXING_GAIN,0.5

MNT_RC_IN_TILT,0 - (for our camera gimbal)

PTCH2SRV_D,0.04 - (increased for tighter tune)
PTCH2SRV_FF,0.4
PTCH2SRV_I,0.15 - (increased for tighter tune)
PTCH2SRV_IMAX,3000
PTCH2SRV_P,0.7 - (increased for tighter tune)
PTCH2SRV_RLL,1.15 - (keeps nose more level in turns, less loss of height)

Q_ANGLE_MAX,3000

Q_ASSIST_ANGLE,30
Q_ASSIST_SPEED,0

Q_TILT_MAX,60
Q_TILT_RATE_DN,50
Q_TILT_RATE_UP,200
Q_TILT_TYPE,2
Q_TILT_YAW_ANGLE,13

Q_TRAN_PIT_MAX,10 - (default of 3 resulted in a worrying dip/loss of altitude during transition)
Q_TRANS_DECEL,2
Q_TRANSITION_MS,3000 - (changed from 5 secs, plane transitions quickly so 5 secs seemed too long)

Q_VFWD_GAIN,0.05 - (Wind resistance in hover)

Q_WP_RADIUS,500 - (looser waypoint radius)

Q_WVANE_GAIN,0.2 - (wind vane enable)
Q_WVANE_MINROLL,2 - (activate on 2 deg of roll)

RLL2SRV_D,0.1 - (increased for tighter tune)
RLL2SRV_FF,0.4
RLL2SRV_I,0.2 - (increased for tighter tune)
RLL2SRV_IMAX,3000
RLL2SRV_P,1 - (increased for tighter tune)
RLL2SRV_RMAX,0

WP_LOITER_RAD,80 - (good distance for QRTL transition, allows plane to slow down enough)

WP_MAX_RADIUS,0
WP_RADIUS,10 - (more accurate waypoints, especially with flying grids)

YAW2SRV_DAMP,0.08 - (tuning to stop tail wag)
YAW2SRV_IMAX,3000
YAW2SRV_INT,0.3 - (tuning to stop tail wag)
YAW2SRV_RLL,0.8 - (tuning to stop tail wag)
YAW2SRV_SLIP,0

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Excellent, thanks, Graham!

I want FoxTech to sell their Nimbus foam packaging without having to buy the VTOL. It would be nice for storage or travel.

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Thanks for the details about your experience with the batteries. I also have the Foxtech Nimbus VTOL. (V2) It has the dual battery setup and works just as you described.

Please take a picture of your revised airspeed sensor location. Mine is stuck up on the inside bulkhead and interferes with the battery installation.

Just saw your post about V2 param files. I’ll try to post them as soon as possible.

Hi Gordon,

Thanks, that would be awesome!

Good looking plane! Please post a picture of the balancing stand.

I asked this on the Foxtech FB page as one seems to get a quick response there: "I have installed the PG20 in my Nimbus v1 and it has the A and B plug, I can use 2 batteries but sometimes I want to use 1 battery. If I use 2 batteries then the PG20 is set up to switch from battery A to battery B on transition.

However, if I use only 1 battery connected to plug A then will the PG20 recognize that there is no battery B and thus will not switch and just fly the whole flight on battery A?"

and got this response: “… with one battery connect only, the PG20 can’t work.”

That doesn’t seem like well designed software.

I have confirmed that with only one battery connected to A it will hover fine, just don’t know what it will do when transitioning, will it continue just using the one battery or switch off completely?

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Graham,

Can’t you just switch to FBWA on the ground and see if you still have power?

Not sure, as FBWA would cause a transition event but don’t know if there’s a something that prevents a transition on the ground. I suppose I can do it without props just in case :slight_smile:

Checked with the folks at Foxtech. They say they will have samples of this ‘new’ packaging from their vendor in a week.

NIMBUS-2000-06-21.zip (344 Bytes)
This is the file that was on the SD card. Next I’ll try to copy the running config from the x9d to the SD CARD.

Hi Gordon,

Thanks for the file and packaging information. Assuming the shipping cost isn’t too bad, it would be a nice way to store the Nimbus VTOL if they sell the packaging separately.

Cheers!

Gordon,

The file you posted seems to be some strange .bin log file but it is only 390 bytes. It doesn’t load in Mission Planner and posts this error below. I even tried viewing it with NotePad++ just to see if it was a .param file renamed but it seems to be some small binary file.

“Log Browse will not function correctly without FMT messages in your log.”

P.S. I just noticed above that you refered to the X9D SD card. We want the Pixhawk .param file which is stored on the Pixhawk SD card according to FoxTech. Alternatively, you can connect with Mission Planner and save the parameters to a disk file from the Full Parameter List screen under the Config/Tuning section.

Greg, I think that .bin file is the Taranis X9D model file.