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Old May 25, 2009, 01:01 AM
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Meopham, Kent UK
Joined Jul 2008
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Micro Hexrotor

For your interest here are some details of our work on a micro sized hexrotor concept based on Silverlit 45mm Xtwin props and coreless motors.
Not entirely new since others have also done similar before.

4 prototypes have been made in various configurations weighing from 29g to 34g. Size is roughly 6" prop tip to tip.
Flight times can be upto 14minutes with 400mAh single cell but a more appropriate 250mAh gives 10minutes of fairly spirited flying. The camera version will go for about 8minutes. Performance is good in the wind, having tested in upto 20mph. Overall speed is extremely quick - unmeasured but now estimated at 40mph.

35MHz Version

Spektrum Version

They have been used as a testbed to refine our 4.5g breakout control board which includes 3 gyros, tri-axial accelerometer, and a barometer capability.
Additionally the board has 2x switched 5V outputs, 2xUART, SPI and I2C, 3V7 to 5V convertor.

Motors are unstressed - brush wear and temperature negligible, >30 hours tested on some samples. We have a special technique of driving them that improves efficiency, brush wear and control response time. RC control interface is fairly flexible, optionally 35MHz PPM, 2.4GHz Spektrum DSM2 using their remote RX and UART or 868MHz using a two-way packet modem (so we have real time flight telemetry).

Control algorithms are evolving and work is ongoing, mainly software........... but also some additonal hardware features.

Steve
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Last edited by airbotix; May 25, 2009 at 01:48 AM.
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Old May 25, 2009, 09:29 AM
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SebastianJ's Avatar
Denmark, Capital Region of Denmark, CPH
Joined Mar 2006
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Beautiful!

Are you planning to market the controller?
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Old May 25, 2009, 12:32 PM
Registered User
Meopham, Kent UK
Joined Jul 2008
136 Posts
Potentially yes - though what you see is a first step.

Software is fairly bespoke at the moment, and PCB hardware is undergoing some feature additions. The current control board has breakouts on it designed to ease prototyping and tests.

Steve
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Old May 25, 2009, 12:45 PM
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lazer155's Avatar
Phoenix, Arizona
Joined Jan 2009
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So would you sell the controller and people would beable to wire it up to 6 motors in their choice of configuration? Such as a tricopter arrangement with 2 motors stacked at each arm.
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Old May 25, 2009, 01:46 PM
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Meopham, Kent UK
Joined Jul 2008
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Configuration for X, Cross, Hex or Tricopter are all possible - it is a simple mixer algortihm to define each one. The exact definition of what the board does is really down to the software.

More so, fixed wing and swashplate applications are also being considered.
Currently the PCB supports 6 PWM outputs that may drive servos, or suitably fast motor controllers. The control loop tick rate is 1kHz. I2C support is included but we have seen some issues with this (I2C lockup), and prefer PWM. The main aim is to keep everything as light as possible. PCB is currently 1.0x1.5" and weighs 4.5g.
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Old May 25, 2009, 02:05 PM
13brv3's Avatar
Navarre, FL
Joined Mar 2002
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Very cool project Steve!

It does seem to be a challenge filming something that small

Cheers,
Rusty
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Old May 25, 2009, 02:44 PM
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stockholm sweden
Joined Jul 2007
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wow, it looks great!
I would be interested if you ever plan to sell the controller!

keep up the good work!

/Bjorn
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Old May 25, 2009, 03:03 PM
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Phoenix, Arizona
Joined Jan 2009
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I will defientetly buy one!
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Old May 25, 2009, 04:23 PM
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Meopham, Kent UK
Joined Jul 2008
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Quote:
Originally Posted by 13brv3
Very cool project Steve!

It does seem to be a challenge filming something that small

Cheers,
Rusty
The other half did rather complain about filming the second video.

We will see where it goes from here and keep posted.
The current airframe design as it stands using Silverlit parts makes a pretty good fun-fly. Also great for nose in hover training aid having both endurance and hands off stability. Crash reistance is great - minimal cyano required to tack things back together or more usually no damage if on grass.

Aspirations are for a more technical features and greater endurance at this scale - we have a few things in motion at the moment. Should end up with a generic flight control board for potentially multiple applications.

Steve
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Old Jul 11, 2009, 03:53 PM
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Meopham, Kent UK
Joined Jul 2008
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Micro Hexrotor update

Just a small test, but some video with on screen display. Will do some outdoor stuff when weather improves.
Battery voltage, RSSI, attitude, altitude and vario displayed.
The small offest in roll angle needs nulling out.
UAV controlled via 868MHz packet modem.
Telemetry overlaid at RX using data transmitted from UAV at 868MHz.

Work in progress!

Micro hexrotor UAV with onboard video (1 min 38 sec)
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Old Jul 12, 2009, 08:40 AM
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stockholm sweden
Joined Jul 2007
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great work as always!

where did you buy your cam+tx?
I have been looking for a really small setup for my jumpjet..

/Bjorn
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Old Jul 12, 2009, 03:16 PM
Registered User
Meopham, Kent UK
Joined Jul 2008
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Camera from: http://www.microcameras.com/micro_ca...mos_camera.htm

TX from:
http://www.intelligentflight.com/web...er-P43C11.aspx

Both seem OK. Camera is NTSC.
Need to be careful of PSU induced noise on TX - ferrite bead mostly solved my issues (motor PWM noise was picked up)

Rangevideo, RF-Links and Microcameras have alternative TX's.
Electronics123.com also have a small analogue camera from Omnivision.

Steve
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Old Jul 12, 2009, 04:28 PM
I HOOVER because I SUCK!
Portland,Oregon U.S.A.
Joined Sep 2007
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very very nice

I want one bad!

especially if I will be able to run bl motors of it

any plans for that?

mk
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Old Jul 12, 2009, 04:51 PM
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Australia, NSW, Blacktown
Joined Dec 2006
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Iam now subscribed.
Wipes drool from lips.
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Old Jul 13, 2009, 04:18 AM
Registered User
Meopham, Kent UK
Joined Jul 2008
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Quote:
Originally Posted by microkites
very very nice

I want one bad!

especially if I will be able to run bl motors of it

any plans for that?

mk
We do have plans in that area. A small fast & efficient BL controller has already been prototyped at breadboard level. The Silverlit coreless motors are pretty good though a little underpowered, 5g thrust is their optimum.
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