Quad/Hexa-Copter using Propeller, Gyros, Accelerometers, Compass, Pressure & GP

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Comments

  • Robert TRobert T Posts: 71
    edited March 2010 Vote Up0Vote Down
    I started down this road myself about a month ago. I purchased a trial motor/ESC as well as an RC helicopter with Spektrum receiver/transmitter.

    I have both the Arduino Mega board and the Propeller demo board and Propeller robot control board as well as various sensors. I have been writing code or examining others code for each sensor independently to determine their capabilities. I have not tried the Ardunio 5DOF board yet.

    I also purchased the PropScope to look at the signals coming out of the Spektrum Receiver.

    My first project will be to use the Propeller as a simple pass through from the Spektrum Receiver to the motor ESC.

    I like the Arduino Mega since has ADC built in but its hard to beat having 8 cogs. So i will probably use the Propeller or may be a combination of both. My biggest concern with the Propeller is the amount of memory.

    I will post my findings and progress here. I look forward to following this thread.
  • SzabiSzabi Posts: 58
    edited March 2010 Vote Up0Vote Down
    Hi Cluso!

    A few hours back I just replied to your post in Jason's thread. Sorry but I missed yours ... probably because its brand new smile.gif
    I'm definitely interested in building a hexacopter but a quad one. As I have seen this German wonder has great stability. I guess is more stable than a quad one, i simply love it and would like to have something similar.
    A grate extra in addition to the german hexa would be to build a Paradox quadcopter style frame which has a kind of protective ring around the blades ... this could save crashes smile.gif

    I would also follow the idea used by the Hexacopter where separate controllers were build for each motor. It's a bit more costly but also more flexible. This could make task easier for the prop and programmer too, moreover would be a nice to know that a modification to a quad or optocopter will also be possible.

    Finally I'm ready for brainstorming with somebody who wants to build a hexacopter!
    Lets do it! smile.gif
  • HannoHanno Posts: 1,130
    edited March 2010 Vote Up0Vote Down
    Hi,
    I'm very interested in quadrocopter's too.
    I started with RC boats when I was 5- then came cars, gliders, gas control line, electric control line, electric glider, gas heli- and now I fly my Align TREX to take my brain off of programming. I'm almost flying acrobatic with the heli- loops/rolls- works fine in the simulator (fms) but still scared of the fast-approaching-ground.
    I used a 3 axis digital (i2c/spi) accelerometer in my dancebot so quite familiar with that- also single axis gyro- which I fused with a Kalman filter. I second the suggestion to start with a foamie- and lots of time in the simulator. I love the hardware simplicity of a quadrocopter- just 4 motors with propellers. Software can be as complex as you want- and seems ideal for the Propeller.
    Hanno

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Co-author of the official Propeller Guide- available at Amazon
    Developer of ViewPort, the premier visual debugger for the Propeller (read the review here, thread here),
    12Blocks, the block-based programming environment (thread here)
    and PropScope, the multi-function USB oscilloscope/function generator/logic analyzer
    Professional IDE to edit, debug, and run SPIN, PropBasic and C: ViewPort
    Visual programming language: 12Blocks
    Multi-function Oscilloscope/LSA/Function Generator: PropScope
    500 page book of Propeller Projects:Programming and Customizing the Multicore Propeller
    Blog:http://onerobot.org/blog
  • Cluso99Cluso99 Posts: 12,962
    edited March 2010 Vote Up0Vote Down
    I think the quad with the right sofware assistance will be easier to fly than a foamie. At least that is what I am hoping.

    Hanno, it will be great to have your assistance with this project as you have done so much in this area with your dancebot.

    Initially I see we can fly this tethered to a laptop so we can control via serial.Maybe then advance to ZigBee or similar before we let it lose with full RC.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Links to other interesting threads:

    · Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
    · Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
    · Prop Tools under Development or Completed (Index)
    · Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
    · Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
    My cruising website is: ·www.bluemagic.biz·· MultiBlade Props: www.cluso.bluemagic.biz
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • Robert TRobert T Posts: 71
    edited March 2010 Vote Up0Vote Down
    nghobbies now sells complete kits and parts for the Mikrocopter products:

    http://www.nghobbies.com/cart/index.php?main_page=products_all&disp_order=4

    Mikrocopter also has a US site

    http://www.mikrokopter.us

    Here are some others sites of interest

    http://skymixer.engineering.free.fr/
    http://www.rcgroups.com/forums (This site has several several discussions of this topic under multi-rotor-helis)
    http://bogoframe.com/cms/
    http://www.quadroufo.com/
    http://uavp.ch/moin (This is an open source quadracopter project)
    http://asctec.de/main/index.php?id=15&pid=16&lang=en&cat=hobby
    http://www.nicoleto.com/NicoletoMK/Home.html (The best frame design)
    http://diydrones.com/profiles/blogs/ardupilot-main-page (using the Arduino IMU board as an autopilot)

    Knowing little about brushless motors and controllers and props, I looked at what others were using.

    It seems most have chosen an 1000kv to 1500kv brushless outrunner motor with a matching controller.
    The props are typically 10 inches length and 4 inch pitch
  • markaericmarkaeric Posts: 282
    edited March 2010 Vote Up0Vote Down
    Cluso,

    I've been toying with a similar idea lately. However, I was thinking about replacing the individual motors/props at each, with one or two central ducted fans feeding a common plenum into four ducts with downward-facing nozzles at each end. Airflow through each duct would be controlled by butterfly valves similar to those used in throttle bodies, and (maybe?) some thrust-vectoring at each nozzle end. To make things more clear, I've attached a beautiful MS Paint rendering.

    fanf.jpg
  • Cluso99Cluso99 Posts: 12,962
    edited March 2010 Vote Up0Vote Down
    markaeric: That's an interesting thought. I think you will need to angle the nozzles to counter the motor torque (or whatever the correct term is). Somewhere I have read about angling the motors and using same rotation propellors instead of 2 reversed.

    In your design, is a large portion of the airflow going straight down in the center?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Links to other interesting threads:

    · Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
    · Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
    · Prop Tools under Development or Completed (Index)
    · Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
    · Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
    My cruising website is: ·www.bluemagic.biz·· MultiBlade Props: www.cluso.bluemagic.biz
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • HannoHanno Posts: 1,130
    edited March 2010 Vote Up0Vote Down
    Nice thing about quadrocopter is the simplicity of hardware, so I recommend against ducts/vectored stuff.
    A "tricopter" is possible- using a servo to rotate the craft.
    I really like quadrocopter:
    - increase thrust to all 4 motors to go up
    - increase thrust to 2 back motors to go forward
    - increase thrust to 2 side motors to go sideways
    - increase thrust to 2 diagonal motors (which turn clockwise) to turn
    I'm working with Chad on a project related to this- will be unveiled a bit later. I'll monitor this thread.
    Hanno

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Co-author of the official Propeller Guide- available at Amazon
    Developer of ViewPort, the premier visual debugger for the Propeller (read the review here, thread here),
    12Blocks, the block-based programming environment (thread here)
    and PropScope, the multi-function USB oscilloscope/function generator/logic analyzer
    Professional IDE to edit, debug, and run SPIN, PropBasic and C: ViewPort
    Visual programming language: 12Blocks
    Multi-function Oscilloscope/LSA/Function Generator: PropScope
    500 page book of Propeller Projects:Programming and Customizing the Multicore Propeller
    Blog:http://onerobot.org/blog
  • Harrison.Harrison. Posts: 484
    edited March 2010 Vote Up0Vote Down
    There's actually a commercial quadcopter controller based on the Propeller: quadpowered.com/. It's partially open source (or so the author claims). There are a bunch of videos of quadcopters using the QuadPower control board and they all look super stable and 'easy' to fly. From my limited research, I would say they have the second best control board for quadcopters (the best being the Mikrokopter board).

    Multi-rotor aircraft (quadcopters, hexacopters, etc) are really popular now. Even my university senior design group is building a quadcopter (we are using an ARM Cortex-M3 running a custom RTOS).
  • Cluso99Cluso99 Posts: 12,962
    edited March 2010 Vote Up0Vote Down
    Harrison: There is definately a lot of info about these on the internet.

    Hanno: From what I understand, mostly they fly in a "+" rather than "x" format, meaning the forward motor is slowed and the rear is increased to dip the front to fly. They usually paint the forward beam (red) to identify it. The best part is it is only software smile.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Links to other interesting threads:

    · Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
    · Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
    · Prop Tools under Development or Completed (Index)
    · Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
    · Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
    My cruising website is: ·www.bluemagic.biz·· MultiBlade Props: www.cluso.bluemagic.biz
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • BuildThingsBuildThings Posts: 31
    edited March 2010 Vote Up0Vote Down
    @Cluso99

    I just finished reading over the thread and it looks like a very ambitious (yet fun) project. I have been flying RC planes for about 20 years and over the past 3 years have been tinkering with some POV (Point of View) as well as partial UAV projects. I say partial because I have yet to perfect an automated tricycle gear landing. I am also a pilot with a Marine Corps system engineering background and have just loved to tinker in this arena.

    I will toss out a few items to think about, and will post some fixed wing projects I have worked on in the past. I would be interested in building a UAV rotor craft as you build yours.


    1.) Realistic performance standards/specifications and defined operational environment

    COA A.) "total" take off and landing platform(airframe w/ 4 rotors mounted on vertical masts) capable of outdoor autonomous flight with banking angles up to 30' , within a 2 mile radius in winds <2kts

    COA B.) Manual TO/LND platform capable of on demand waypoint navigation using 10' bank angle turns from established flight within a 1/4 mile flight radius.

    Course Of Action A takes on the complete flight profile and defines an operational context that is very complex in terms of extended flight distance, wind compensation, not to mention the dreaded takeoff and landing.

    COA B I think is the most feasible place to start since you will still get to play with every bit of cool technology, but without some of the variables that normally make people toss all their parts in a box and give up. This way you can stay motivated as you complete fun tasks [noparse]:)[/noparse] , vice spending months trying to calculate the best way to sense, calculate, and control glide slope for the landing roll.

    I have normally started out UAV projects by systematically adding gyro-stabilization or a steer-to heading features on an aircraft I have been manually flying. You need to get an idea of what the magic dust needs to do. Most importantly you need to ensure that you have built an inherently stable aircraft.

    **Too many builders end up spending magnitudes of development time trying to compensate with software for the mistakes they made with the hardware. **

    Specifically- Especially important items are ; weight and balance, motor placement/pitch, rotor length/pitch

    You could easily double or triple your processing requirements resulting in increased cost/weight/complexity, if poor Propeller is trying to compensate for a crippled bird.



    2.) Ultrasonic/radio altimeter to supplement/replace pressure sensor

    I have always used ultrasonic/radio altimeters for their precision of ~2cm as compared to the ~25cm of the BMP085. This extra resolution will prove to be very valuable when dealing with getting in and out of ground effect. Actually without this precision you will end up with more of a semi controlled crash at best when it comes to takeoff/landing or hovering in ground effect.


    3.) Recovering from "bad attitudes"

    Spend a few cycles brainstorming "self righting". Not sure how many folks use this term but it refers to the self correction actions from the evils of Newton and Murphy. My main thought is that until you have nearly perfected the self righting routine, altitude is your friend and a manual control system is your lifeline. I mention this because it is fairly easy to cook up some code that navigates an inherently stable aircraft along GPS waypoints using gyro stabilization. The inertial navigation system is able to compensate for a good amount of attitude and altitude deviation caused by small winds or recalculation of actual position, however this is more navigation that it is aviation. Once we start talking about extreme attitudes caused by stalls, engine degradation/failure, or a control abnormality the needed software complexity to recover from these situation is magnitudes more complex than following waypoints. This is where aviation comes in. As an example as to when the system must FLY itself, consider a leveling algorithm having a nice clean linear relationship between banking angle and altitude during a 0-20' turn. It is able to be computed in near real time and easily translated into servo or ESC actions.(Simple) This algorithm gets very nasty past lets say 35' when you partially stall out a rotor, decrease lift, and get a hiccup of gyroscopic precession. This can turn into a very unrecoverable situation without some fuzzy logic, some altitude, some thrust… you get the picture.

    Testing results: X= what the aircraft looked like right before it failed

    Design impact: Make sure aircraft never lookes like X


    One last interesting thought since its nearly 2am.

    4.) Control refresh rate.

    I have noticed that most of the mixing algorithms out there are based around the precision of servos. I wonder what type of increase in precision we could gain by tweaking the filters for a no-servo design.



    Cheers,
    John
  • HannoHanno Posts: 1,130
    edited March 2010 Vote Up0Vote Down
    Wow- quadpowered uses 4 Propellers! That's a lot of power... I wonder why?
    Here's how I would start (nothing fancy):
    - drive 4 motor's with 2 h-bridges (4 pins, 1 pasm cog)
    - read 4 channels of pulse input from RC receiver (4 pins, 1 pasm cog)
    - 3 axis digital accelerometer (SPI)
    - 3 axis digital gyro (SPI- source?)- or replace both with a sparkfun 6 axis (1 spin cog)
    - mix the RC input with sensor readings to decide the 4 motor targets (1 spin cog)
    - (personal plug, but this is what I built it for: debug sensors/motors/physics with ViewPort)
    - this leaves plenty of cogs for fun stuff like streaming video to SD card/wireless...
    - I would leave fancy stuff like altitude control for later
    Hanno

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Co-author of the official Propeller Guide- available at Amazon
    Developer of ViewPort, the premier visual debugger for the Propeller (read the review here, thread here),
    12Blocks, the block-based programming environment (thread here)
    and PropScope, the multi-function USB oscilloscope/function generator/logic analyzer
    Professional IDE to edit, debug, and run SPIN, PropBasic and C: ViewPort
    Visual programming language: 12Blocks
    Multi-function Oscilloscope/LSA/Function Generator: PropScope
    500 page book of Propeller Projects:Programming and Customizing the Multicore Propeller
    Blog:http://onerobot.org/blog
  • SzabiSzabi Posts: 58
    edited March 2010 Vote Up0Vote Down
    Hanno,

    H-Bridge? Don't we wanna use brushless motors?
  • Cluso99Cluso99 Posts: 12,962
    edited March 2010 Vote Up0Vote Down
    Hanno:
    Not sure where 4 propellers for 4 motors came from?
    It's not exactly an H-Bridge driver as it uses 6 MosFets to drive the 3-wire motor control. However, driving ESC's may be simpler and easier to start with as they cost about $12-20 each x4. I presume we will require a seperate cog for each motor due to the counter requirements (PWM). Maybe we could control a pair of motors from a cog. First up, make it simple and use 4.

    I see altitude control required fairly early to ensure the craft does not plummet to the ground. It does not have to be fancy and the BM085 should be sufficient. I am interested to see what ultrasonics could do for us too, perhaps when close to the ground.

    BuildThings:
    We would appreciate any help in this project. On this forum most of our expertise is in software and hardware, not airframes. The QuadCopter is a way to extend our designs into something practical. I think it will not be too difficult to make the QuadCopter hover and we can build into the software the extras to allow movement by tipping to a slight angle, etc. As I said above, I think initial flights will be tethered just lifting off the ground and landing. Then tilting, etc.

    Provided we have enought thrust and the frame is stable then the rest is software control, and finally commands from the RC unit. I see the addition of the RC unit as being last.

    There are no servos planned to be used in this project. Where would they be used?

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Links to other interesting threads:

    · Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
    · Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
    · Prop Tools under Development or Completed (Index)
    · Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
    · Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
    My cruising website is: ·www.bluemagic.biz·· MultiBlade Props: www.cluso.bluemagic.biz
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • BuildThingsBuildThings Posts: 31
    edited March 2010 Vote Up0Vote Down
    @Cluso99

    Not a problem, anything I can add and learn will be great. Since I am new to the Prop it gives me something fun to play with also.

    The reason I had mentioned the fact that this did not use any servos was a good thing. When using servos their speed along with "play" in control arms and linkages serve as the weakest link in precise maneuverability.

    Viewport will definitely be your friend [noparse]:)[/noparse]

    To contradict everything that I wrote above... I am going to do some testing this week on motor tilting. My first thought is not to try and use tilt for direction control, instead to improve stability in descending and acceding ground level flight by slightly tilting all motors outboard. This should improve the stability in ground effect.

    The most vulnerable position is going to be at low power and close to the ground. This is because you do not have enough thrust to make timely corrections.. and not enough altitude to make slow corrections. With a copter having no fixed control surfaces the only way to make directional corrections is to add more thrust (or hijack some from the oposite side). Adding power close to the ground in a unstable position will just make you hit the ground faster if the correction fails.

    If you have ever tried to balance while standing on a ball you know that as soon as you start adding large balance correction.. you fall.

    Altitude / ground detection / object detection -- up for more discusion and testing.
  • Harrison.Harrison. Posts: 484
    edited March 2010 Vote Up0Vote Down
    Driving sensorless BLDC motors isn't very straightforward. You have to have at least 1 ADC channel to monitor the back EMF from the motor to detect where the motor shaft is in commutation. Using off-the-shelf Turnigy ESCs is definitely the most cost effective solution (they have a 28-pin 8-bit Atmel micro inside). The Turnigy Plush ESCs supposedly support fast update rates (somewhere between 100Hz - 400Hz updates, much faster than normal servos).

    @Cluso: The Quadpower (quadpowered.com/) product linked above uses 4 Propeller Microcontrollers for their quadcopter controller.
  • Cluso99Cluso99 Posts: 12,962
    edited March 2010 Vote Up0Vote Down
    Harrison: That's a great link smile.gif

    Didn't realise anyone was selling a Propeller kit. I don't see where 4 propellers are used though. There seem to be 2 pcbs with props. The baseboard is not described but the add-on board has a prop.

    Just pondering a little further... (my hardware is packed cry.gif )
    • 1 Propeller
      • read all the instruments from 2nd prop (serial 115200)
      • read RC inputs
      • make calculations
      • control the motors
        • initially using standard ESC's
        • maybe later drive MosFet circuit
    • 1 Propeller
      • read the gyros 3-axis (LY530+LPR530 or LY550+LPR550) [noparse][[/noparse]may need small ADC micro]
      • read the accelerometer 3-axis (MMA7455 or ADXL345)
      • read the digital compass 3-axis (HM5843)
      • read the pressure & temp (BMP085)
      • read ultrasonic sensor (optional) for ground proximity
      • GPS (optional) (PMB-248 or PMB-648)

    Obviously the second prop could be replaced with a 5DOF, 6DOF or 9DOF prebuilt board. However it takes the fun out of it.

    Has anyone found gyros with I2C or SPI output?? The LY530AL seems like it may not work or is being discontinued and there is no matching LPY version (with I2C/SPI)

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Links to other interesting threads:

    · Home of the MultiBladeProps: TriBlade,·RamBlade,·SixBlade, website
    · Single Board Computer:·3 Propeller ICs·and a·TriBladeProp board (ZiCog Z80 Emulator)
    · Prop Tools under Development or Completed (Index)
    · Emulators: CPUs Z80 etc; Micros Altair etc;· Terminals·VT100 etc; (Index) ZiCog (Z80) , MoCog (6809)·
    · Prop OS: SphinxOS·, PropDos , PropCmd··· Search the Propeller forums·(uses advanced Google search)
    My cruising website is: ·www.bluemagic.biz·· MultiBlade Props: www.cluso.bluemagic.biz

    Post Edited (Cluso99) : 3/16/2010 6:19:08 PM GMT
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • HannoHanno Posts: 1,130
    edited March 2010 Vote Up0Vote Down
    For brushless I'd definitely use off-the-shelf controllers- so we just need the servo32 object to generate the 4 pulses. I still think it's easily possible to keep this in 1 Propeller- that drastically reduces complexity. Ground effect helps quite a bit when flying a helicopter- it basically feels like a "pillow". Once you're out of ground effect you'll be using quite a bit more thrust, so if you happen to re-enter ground effect, you'll typically bounce off without hitting ground. Starting out of ground effect is simple, just apply enough thrust to go up ~ a foot. Going down is simple too- without complex mechanical things to break, you could fall the last foot- especially onto soft surfaces like grass. To start with, we need to control the quadrocopter via RC- with the Propeller mixing our inputs with the sensors to make the thing flyable.
    Oh- I doubt a compass is usable- the one I used on DanceBot (HB55) was very sensitive to being tilted.
    Hanno

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Co-author of the official Propeller Guide- available at Amazon
    Developer of ViewPort, the premier visual debugger for the Propeller (read the review here, thread here),
    12Blocks, the block-based programming environment (thread here)
    and PropScope, the multi-function USB oscilloscope/function generator/logic analyzer
    Professional IDE to edit, debug, and run SPIN, PropBasic and C: ViewPort
    Visual programming language: 12Blocks
    Multi-function Oscilloscope/LSA/Function Generator: PropScope
    500 page book of Propeller Projects:Programming and Customizing the Multicore Propeller
    Blog:http://onerobot.org/blog
  • markaericmarkaeric Posts: 282
    edited March 2010 Vote Up0Vote Down
    Cluso, if 1 fan is used, then it is likely that some of the thrust would need to be vectored to counter the torque. This is partially why I suggested more than one fan (will probably need the additional thrust anyways). The design I have in mind vaguely resembles the drawing, it's just my attention and patience for MS Paint is limited. The bottom the the plenum is sealed, so all thrust is directed to each "arm".

    Hanno, the propeller design would most likely be easier, but it's also been done many times over. To be fair, though, my inspiration for the design came from this concept: http://www.aerobiker.com/
  • hover1hover1 Posts: 1,927
    edited March 2010 Vote Up0Vote Down
    Coaxial or counter-rotating blades would be much easier to do than thrust vectoring to counter torque. But to navigate, it would require a gimbal system to tilt the whole motor/propeller assembly.

    Simple motor speed control in a quad or hex configuration seems much less complicated to achieve, and less moving parts.

    I would stay with off the shelf ESC's for the initial design because they are plentiful and proven. The one I use in my planes and Heli's are appropriately named Jeti Spin. Used in conjunction with the JETI Box, you can record min-max current, temp, set parameters for the motors and more. The company, (Model Motors), also has a line of 2.4 GHz transmitter/receiver/sensor devices that can relieve the propeller of some of the tasks of recoding environmental readings and downloading them to the ground.

    Just my input,

    Jim

    Their current catalog can be viewed here:

    http://www.modelmotors.cz/download/katalog_2010_hr.pdf

    markaeric said...
    Cluso, if 1 fan is used, then it is likely that some of the thrust would need to be vectored to counter the torque. This is partially why I suggested more than one fan (will probably need the additional thrust anyways). The design I have in mind vaguely resembles the drawing, it's just my attention and patience for MS Paint is limited. The bottom the the plenum is sealed, so all thrust is directed to each "arm".

    Hanno, the propeller design would most likely be easier, but it's also been done many times over. To be fair, though, my inspiration for the design came from this concept: http://www.aerobiker.com/
    [url=http://][/url][url=http://][/url][url=http://][/url]

    Post Edited (hover1) : 3/16/2010 8:16:43 PM GMT
    I have three propellers
  • hover1hover1 Posts: 1,927
    edited March 2010 Vote Up0Vote Down
    One retailer in Australia is:

    http://www.pht.net.au/store/index.php/hobbies/

    but they don't seen to have any Jeti Spin ECS' in stock.

    Another is:

    shop.singahobby.com

    but that site times out here in the US.

    Jim
    I have three propellers
  • Graham StablerGraham Stabler Posts: 2,507
    edited March 2010 Vote Up0Vote Down
    markaeric, fans are not really very good at creating static thrust so I think that design would struggle.

    Graham
  • markaericmarkaeric Posts: 282
    edited March 2010 Vote Up0Vote Down
    Graham, I suppose it completely depends on the design. Most large scale ducted fans work great a low speeds, where the drag of the shroud is not such an issue. This may be different for scale model ducted fans where they're usually utilized in fast "jet" models. My biggest concern would be with the fact that fans/propellers don't generate significant pressure, which could cause the design to be a complete flop. There is at least one way to find out...

    Post Edited (markaeric) : 3/16/2010 9:01:23 PM GMT
  • Robert TRobert T Posts: 71
    edited March 2010 Vote Up0Vote Down
    I would stick with standard prop drive and probably use what has been proven to work.

    The Mikrocopter site offers two motors for sell for their copters

    1. eSky Brushless Outrunner EK5-0002B
    2. Robbe Roxxy Brushless outrunner 2815

    I would start with one of these or a motor of equivalent rating. The eSky motor is 1000Kv (RPM/V), Max Current 8A, 45 grams, requires 25A ESC. The Roxxy is 1100 rpm/V, 7A, 33 gram. Both have 79% efficiency.

    Mikrocopter has built their own speed controllers($60 US). They can be purchased from the nghobbies web site. It is stated that they built their own controllers for faster response, but I don't know how standard ESCs compare.

    Propeller blades are typically 10 inch 4.5 inch or 12 inch 4.5 inch.

    LiPo batteries are typically 3 or 4 cell

    This page gives a summary : http://www.mikrokopter.de/ucwiki/en/KomplettsetUebersicht.
  • Robert TRobert T Posts: 71
    edited March 2010 Vote Up0Vote Down
    Here is more detailed information on the brushless controller built by Mikrocopter group.

    http://www.mikrokopter.de/ucwiki/en/BrushlessCtrl

    Basically:

    Response time: < 0.5 ms
    I2C bus interface
    30 A MosFets
    CPU: Atmel Atmega8
    Continuous 55W, Peak (several seconds) 120W
  • hover1hover1 Posts: 1,927
    edited March 2010 Vote Up0Vote Down
    @all

    I don't think it has been addressed in this thread, but on a quadcopter or hexcopter for that matter, an even number of motors will be rotating clockwise, and the others need to be rotation counterclockwise, OK anti clockwise. This is because there is no tail rotor to compensate for the torque of the rotating motor as in a single rotor helicopter. The torque will be cancelled out. This means that the appropriate props must be purchased. One meant for "puller" and one meant for "pusher".

    I know most of you already know this, but I wanted to put this out to people that many be unfamiliar with the non-tail rotor type of craft.

    Jim
    I have three propellers
  • Graham StablerGraham Stabler Posts: 2,507
    edited March 2010 Vote Up0Vote Down
    markaeric,

    You can think of small ducted fans like any other propeller in many ways, small diameter high revs is great for high air speed where as large propellers/rotors turning more slowly are great for slow/no air speed. The quad copters take a practical middle ground where they can make use of increased torque from the outrunner motors and turn big props while not using such big props that they would require gearing. But like you say there is a way to find out. There is a UAV built with a single ducted fan, that works so there is hope:

    www.defenseindustrydaily.com/images/AIR_UAV_FCS_Class-I_Honeywell_MAV_Launch_lg.jpg

    Making the fan diameter big will help no end too.

    Graham
  • hover1hover1 Posts: 1,927
    edited March 2010 Vote Up0Vote Down
    Creating efficient thrust with ducted fans is not an easy proposition. We deal with this all the time with our hovercrafts. Correct bell inlet design, duct length, fan size, duct taper all come into play. We have tried counter rotating props, and air straighteners but have not gained too much added, but all was added with much more cost due to mechanical add-ons. And this is just to go horizontal. Going vertical needs much more efficiency.
    The last UAV I recall that ran well was:

    http://en.wikipedia.org/wiki/Sikorsky_Cypher

    I used to have a video of it, but can't find it now.

    Jim


    Graham Stabler said...
    markaeric, fans are not really very good at creating static thrust so I think that design would struggle.

    Graham
    I have three propellers
  • hover1hover1 Posts: 1,927
    edited March 2010 Vote Up0Vote Down
    Well, Graham just came up with better UAV!

    If we had stuff like that back in the 70's, I would have signed up for the military a little sooner!

    Jim
    I have three propellers
  • BuildThingsBuildThings Posts: 31
    edited March 2010 Vote Up0Vote Down
    @Graham

    I for one think that ducted fans are awesome and have done some thrust vectoring with RC foamies . In comparison however, that one from Honeywell was part of a 61 million dollar contract and used a gas engine [noparse]:)[/noparse]

    Here is an interesting build using 4 ducted fans.
    www.fpv.lt/lang/en/2009/12/pristatytas-turbininis-keturstraigtis-panasus-i-avatar-filmo-skraidanti-irengini-new-ducted-fan-quadcopter-was-introduced-by-cyber-technology/

    I definitely like how the design leaves nothing exposed to break and get smashed up.
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