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Quad/Hexa-Copter using Propeller, Gyros, Accelerometers, Compass, Pressure & GP - Page 5 — Parallax Forums

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

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Comments

  • Graham StablerGraham Stabler Posts: 2,507
    edited 2010-03-20 22:49
    kf4ixm said...
    @dMajo
    Sorry, while i respect your right to disagree with me, your comment saying that i am wrong without proving that im wrong it is just plain rude. sure there's some cost involved, but buying parts in bulk as most companies do, i still say theres not that much cost in the production.
    dMajo said...

    I think that the price is a bit high and I think also that kf4ixm is wrong.

    Most of the costs will be in development but that has to be paid for. Of course there may be an element of "charge what we can get away with" as you get in medicine and the military. We also tend to forget the costs of tooling (injection moulds for example) which for a a product such as this with fairly limited production numbers will be significant.

    Graham
  • dMajodMajo Posts: 855
    edited 2010-03-21 00:03
    kf4ixm said...
    @dMajo
    Sorry, while i respect your right to disagree with me, your comment saying that i am wrong without proving that im wrong·it is just plain rude. sure there's some cost involved, but buying parts in bulk as most companies do, i still say theres not that much cost in the production.
    dMajo said...
    I think that the price is a bit high and I think also that kf4ixm is wrong.
    kf4ixm, which part of the words "I THINK" do you not understand? It was just a personal opinion not an assumption, I think I haven't to provide proves for opinions.

    I have experience (beside electronics of course) with carbon's fiber, plastic molding, turning/turnery, milling, welding ... because·of·6 years of working for the automotive industry (developing machinery for car front/rear-lamps production lines) so I just thought that your evaluation was too small. I thought that this is a niche product where the sale quantities are not big thus not having advantage from bulk parts buying. But as I said RC modelling is not my field

    Moreover if you are able to sell me Draganflyer X6 Helicopters or equivalent clones (same specs or better) for $1500 each, I'll buy three immediately.

    I hope my english is clear enough

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  • hover1hover1 Posts: 1,929
    edited 2010-03-21 00:35
    No harm, no foul. Like I said, I would be happy to start a discussion in the Sandbox if you want. All positive.

    Jim
    kf4ixm said...
    i apologize to all, should have kept my mouth shut. i will delete this post within the hour asit does not pertain to the original posting.
  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-21 05:44
    Robert: Thanks for the Ping))) results. Now we can settle on this sensor because it is easy to plug into.

    Graham: I agree we can mount the pcbs seperately with antivibration or whatever. But, if I make the power board able to also be used (even if seperately) as the frame connector, it will reduce the pcb costs of the power board.· Look at it this way, whatever amortisation costs for the power board are, the extra cost for a pair of frame boards would only be ~$5+ and they would be strong (I think), predrilled,·and·look professional·(sorry only green with white overlay) so our Copter would look nice. To get the boards in black or red would x4 the cost - my TriBlade is black.

    I have been doing a little more research and maybe I will post a block diagram of the controller/sensor board later today.

    FYI: The 9DOF pcb is 1.95"x1.1" which is almost the same size as my RamBlade pcb 1.9"x1.2".

    Motors...
    I am thinking of getting 2 sizes of motors, 1000kV & 890kV and 25A BESCs. It is better to get the combo with the BESC
    TowerPro 2409-18T & 25A BEC + prop 9x4.7 $19.95·http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=4712&Product_Name=TowerPro_BM2409-18T_/_25A_BEC_/_9x4.7_Prop_Combo
    TowerPro 2410-08T $6.95 http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=664&Product_Name=TowerPro_Brushless_Outrunner_2410-08T_890kv

    Batteries...
    Here are some (I have ignored nil stk batteries). I guess I will need to try both 2S & 3S so maybe the 2650mA 2S & 1800mA 3S might be a good start. I have gone for high discharge since we will have 4 (or 6) motors and I would prefer to use 1 battery.
    **Turnigy 2650mAh 2S 40C discharge 180g $16.11 http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=10293&Product_Name=Turnigy_2650mAh_2S_40C_Lipo_Pack
    Turnigy 3000mAh 2S 40C discharge 198g $18.44 http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=10297&Product_Name=Turnigy_3000mAh_2S_40C_Lipo_Pack
    **Turnigy 1800mAh 3S 40C discharge 247g $15.90 http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=10290&Product_Name=Turnigy_1800mAh_3S_40C_Lipo_Pack
    Turnigy 3000mAh 3S 40C discharge 278g $28.35 http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=10298&Product_Name=Turnigy_3000mAh_3S_40C_Lipo_Pack

    Propellers... (Thanks Roy. ·How do they go with your motor? and are you using 2S or 3S batteries?)
    3·Blade 8x4 $2.79 pr counter rotate http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=5249&Product_Name=GWS_HD8040_3_Blade_Prop_Counter_Rotate_(2pc)
    3 Blade 8x4 $2.79 pr normal http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=5247&Product_Name=GWS_HD8040_3_Blade_Prop_(2pc_pack)
    I may also buy 9x5 3-Blade as well to try with the more powerful motors.

    Thought I may also try
    2 Blade 9x3.8 Slow fly propeller $1.20ea http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=6224

    I am going to order these 10.5x10.5x750mm carbon fibre tubes for my frame 49g $4.04
    http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=9012

    I already have these...
    Prop saver $1.49ea http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=3738
    Charger 12V 2S or 3S $5.95 http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=6507
    Battery monitor $2.99 http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=6589

    Once again shipping is a·fair bit·extra.

    Any comments???
    Have I forgotten anything???

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    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) : 3/21/2010 6:37:06 AM GMT
  • Roy ElthamRoy Eltham Posts: 2,996
    edited 2010-03-21 07:59
    I'm using 2560mAh 3S 30C batteries. I currently have one battery per 2 motors. Each motor is 1500kV and 8A max with normal draw being 2-6A. I could run all 4 motors from one battery with a shorter flight time if needed.

    The propellers seem to work reasonably well with my motors. They are very lightweight. I think I could go with a little bigger size to get more lift. I'm not using PropSavers, it's just a nut clamping down a big washer-like thing to hold them on the shaft. Previously I had thought they were slipping at high throttle, but what's actually happening is that the motors can't handle over a certain (very high) throttle level and they "stall" for lack of a better word, but I can configure things to not go that high and avoid that.

    So, today I put the H48C and the Gyros onto the Prop Protoboard as well as the stuff to interface with the receiver and the ESC's. Using Jason Dorie's software as a starting point I have managed to get the thing driving the motors based on user input from the receiver. I have it going through Jason's Kalman filter and simplified PID, but I still need to dial in the numbers. It's not stable at all, but all the bits are functioning. I can see the raw and filtered numbers for the gyros and acellerometer in PST, and even with the motors running they don't look terrible. Right now it appears the main issue is that it's over-correcting. Plus, I'm not certain I got things fully changed over properly to account for the differences in my Gyros and Acellerometer compared to the ones Jason was using in the final version the software is for... Anyway, hopefully tomorrow (Sunday) I can get things dialed in enough for it to at least fly a little bit.

    HobbyKing (HobbyCity) really ups the shipping when you buy the carbon fiber tubes, they need a bigger box and that causes a decent jump in internation shipping cost. I was going to get some when I was ordering my motors, ECSs, and stuff. If they sold shorter lengths that didn't need a bigger box then it would be a lot cheaper.

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  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-21 10:25
    Thanks for the tip on shipping the rods Roy.

    Here is a block diagram. You will note I am considering using a PIC with USB instead of the Atmega. Any thoughts???

    Postedit: Updated Block Diagram to include microSD & connection for 1-pinTV & 1pinKbd


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    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) : 3/21/2010 11:06:40 AM GMT
    1089 x 747 - 54K
  • SzabiSzabi Posts: 58
    edited 2010-03-21 12:49
    Are you considering using a PIC and analog gyros instead of ADC's or the 9DOF for a lower prototype cost? Or did I missed a post where we cancelled using of the ADC's or 9DOF? .-)
    I don't mind using a PIC, I was also thinking to hook up all the analog sensors on it but a USB?...for what purpose? (programming?)

    The plan was to build a sensor board. If so, I would would install all the sensors and controller on the same PCB rather then wiring all of those (Compass, Accelero etc) from sensor board to the Prop board.
    smilewinkgrin.gif
  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-21 13:55
    Szabi:
    My current thoughts are to use a single pcb for the sensors and controller. If it were 2 pcbs then there would only be a 2-wire serial interface + power between the pcbs anyway. The sensor pcb could be replaced with the 9DOF pcb.

    It's my intention to allow the 9DOF pcb to be used as an alternative, and just connect it to the prop via 2-wire serial (i.e. do not fit the sensors and PIC/Atmega/micro). It is just that the sensors are cheaper and quite small so I think it is worthwhile allowing them to be on my pcb.

    I am still thinking about the actual implementation. The 9DOF will be able to be used with my pcb by just not fitting the sensors that are on the 9DOF pcb. While thinking about the sensor section I thought it may be nicer to use a PIC with USB capability inbuilt (only requires a connector). It is able to download and program the prop as if it were a propplug. It has ADC onchip, so it can still interface the gyros. The other alternative is to use the Atmega as the 9DOF does. Cost is marginally less for the PIC. I could also use a cheaper micro to do the ADC. I really looked at using an ADC yet (not sure if I will).

    The prop will read the other sensors directly if they are fitted on my pcb. The GPS will plug into the pcb by cable (2-wire serial + power).

    I was reading up on the gyros and they actually have an acceleronometer onchip as well. It's a pitty we cannot access them as well :-( The onchip ASIC uses this and the gyro to calculate and output the angular motion.

    I still am working on a few ideas, so nothing is in concrete and I am still waiting on any comments.

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    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
  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-21 14:19
    OK, here is my latest thinking. It seems more futureproof...
    • Controller & Sensor PCB...
      • Propeller & eeprom
      • Gyro alternatives
        • Gyro L3G4200D (onboard 3-axis digital·when·available)
        • Serial I/O to external gyro pcb (see below)
        • Serial I/O to 9DOF pcb
      • Accelerometer ADXL345
      • Digital Compass HMC5843
      • Pressure & Temperature BMP085
      • Ultrasonic (Parallax)
      • microSD
      • Serial I/O (2-wire)
        • external GPS (PMB-248 or PMB-648 from Parallax)
        • also used to program the propeller
      • RC PWM inputs x8
      • ESC PWM outputs x8
    • Gyro PCB...
      • a breakoff pcb
      • LPR530AL gyro (or LPR550AL)
      • LY530AL or LPY530AL gyro (or LY/LPY550AL)
      • PIC or Atmega micro or other micro (undecided)
      • Serial I/O to Controller & Sensor PCB

    Your thoughts and comments please???

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    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
  • Robert TRobert T Posts: 71
    edited 2010-03-21 14:25
    Cluso

    On your diagram you have only one line for input from the RC. I assume that this quad/hex would fly mostly by RC and all the other input is for stable flight(pitch/roll/yaw), hovering, etc. Eventually the goal would be for autonomous flight or at least semi-autonomous.

    Given that then I would think you would need input for Height(Motor power), Yaw, Pitch and Roll. Possibly on an on/off toggle for hovering or autonomous flight or some other pattern. That would mean 5 channels at least.

    Thats the way my RC Helicopter is set up. I have a 7 channel transmitter and receiver(Spektrum). Five of those outputs from the receiver are used.
  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-21 14:43
    Here is a link about what's inside the ST Gyroscope chip. Nifty smilewinkgrin.gif

    http://www.st.com/stonline/domains/support/epresentations/memsgyroscopes/gyros.htm

    Robert: Those lines represent 8 channels. So 8 RC inputs and 8 ESC outputs. We probably will not need them all, so they may be used for something else. I have a 6 channel Spektrum. tongue.gif

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    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
  • A. ESERA. ESER Posts: 24
    edited 2010-03-21 21:45
    Hi All,

    I am also working on a propeller chip based quadcopter project for a few months. And I want to
    share some of my results, and need your advices on some subjects.

    1- update rate of control loop for quadcopter is critical. A minimum rate of 100 - 150Hz is required. I have modified servo32 object.
    Servo update rate is increased to 200 Hz. But number of servos is decreased to 8. I have attached my servo8 object.
    PLEASE DO NOT USE WITH STANDART SERVOS. THIS OBJECT IS FOR ONLY DIGITAL SERVOS AND ESCs

    2- I am using 2.order complementary filter for attitude estimation. (Up to now it works well) I am using Float32Full object (2 cogs)
    I need to convert Float32Full to fit in 1 cog by deleting unused floating functions. For example Sin(),Cos(),Tan(),Log(),Log10(),Exp(),Exp10() ...
    Critical one is Atan2(x,y) from Float32A object. Any help would be great.

    3- I do not suggest using LPR530AL gyro (or LPR550AL) LY530AL or LPY530AL gyro (or LY/LPY550AL) for Quad and Heli projects. Because these gyros relativly lower resonant frequencies. Please refer to CCPM Helicopter control with DCM algorithm in Diydrones.com. Many vibration issues of these gyros reported there. I am using IDG500 and IXZ500. But I think ADXRS610 is the best gyro around for against vibration issues.

    4- I am also planing to use 2 prop chip with serial communication. But can we use faster way. For example A slave SPI object would be great.
    (we already have master protocol in obex). Any ideas ?

    5- I made a test stand for single motor hover control. And I have implemented PID control using gyro & accel data.
    Here is the video vimeo.com/10330142

    Aydin

    Post Edited (A. ESER) : 3/21/2010 9:50:36 PM GMT
  • Timothy D. SwieterTimothy D. Swieter Posts: 1,613
    edited 2010-03-21 22:56
    S. ESER -

    Nice idea on your bench top test stand! What program were you using for displaying the graph data on your PC?

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    Timothy D. Swieter, E.I.
    www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" LCD Composite video display, eProto for SunSPOT
    www.tdswieter.com
  • Roy ElthamRoy Eltham Posts: 2,996
    edited 2010-03-22 00:11
    Update on trying to get my quadrotor working:

    I played around with the numbers and such today, and it's a little better but not really flyable by me. It keeps leaning off to one side or another right at take off and when I try to correct for it I usually over correct or mess up because it gets turned around. I've broken a couple propellers and scared the Smile out of my cats. [noparse]:)[/noparse] Jason Dorie had said that he used his R/C helicopter fly skills when flying his, and that his software was not self-stable. Since I lack those skills I have to make software that works.

    I need to learn more about PID and Kalman filters, and also build some test rigs I think. So it's going to be a little while longer before I can really fly my quadrotor.

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  • Robert TRobert T Posts: 71
    edited 2010-03-22 00:18
    ESER

    What kind of ESC are you using?

    As you may have read, there has been some talk of using the Sparkfun 9 degrees of freedom board which uses the LY530AL and LPR530AL.

    You are further along than most of us. I just today setup a single motor and ESC to test control.

    Thanks for the info.
  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-22 02:43
    S.ESER: Nice video and test setup. I was thinking of testing with 4 motors and a short tether. Your idea looks simpler to get the basics working.

    Interesting comments regarding the gyros. Could it be the filtering with the ST parts (software). Remember we also have accelerometers. I had pretty much settled on the ST gyros, so now I am wondering?

    Comms between props is simple and you can get Mbps using serial and Beau's method.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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
  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-22 09:56
    On the basis that I/we can substitute any of the sensors by a daughter pcb, I am going to continue on the latest proposed pcb a couple of posts above. In fact, initially, the gyro will have a daughter board (or a breakoff board) to collect the info from the LPR530/550AL & LY/LPY530/550AL. With the now proposed pcb, I will look to just use a cheap micro for the ADC for these gyros and output serial 2-wire or an I2C slave.

    If, as A.ESER suggests, the gyros we are using do not work, we can replace that pcb with another plugin pcb with alternative gyros. The other gyros are much more expensive.

    I am thinking the pcb may end up being ~2x2" plus a breakoff ~1x2" for the analog gyros and micro.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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
  • A. ESERA. ESER Posts: 24
    edited 2010-03-22 18:00
    Timothy -
    The program is simple graphical util(I wrote), and only display IMU data from serial port.

    Robert -
    I am using very simple 20A ESC in test stand. I am going to use TURNIGY Plush ESCs from HobbyKing on QuadCopter. The critical point is how fast you can update the input signal of ESC. Most of ESC manufacturers does not contain information about ESC input update rate. You just have to try.

    Cluso99 -
    I did not try ST gyros myself. Quads have much less vibration issues than Helicopters. ST gyros may work. Your work will show us.
    As far as I know, Vibration at frequencies (or upper harmonics) close to gyros internal resonant frequency, makes gyro signal useless (even with software filters)

    For Comms between props, What is the max rate using serial that you ever tested. I am also planning to use serial. Because Beau's method consumes 2 cogs.

    Aydin ESER
  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-22 18:27
    Aydin: I have only used 115200 between props so far using FDX. I am not sure what the upper limit is with FDX.

    Regarding the harmonics for the gyros... I have not examined the specs closely. Do they all operate at similar frequencies or are they different and hence why some gyros are better than others? I guess if we try to insulate the pcb from the frame to stop vibration issues we are effectively dampening the response of the gyros.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    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
  • A. ESERA. ESER Posts: 24
    edited 2010-03-22 19:22
    I think there is a misunderstanding. Resonant frequency of a gyro is not the gyros operating frequency. Its the point where gyro fails due to resonance. Resonant frequency is not only quality factor for a gyro.
    - Gyros drift over time.
    - Gyros drift with temparature.
  • markaericmarkaeric Posts: 282
    edited 2010-03-22 23:34
    Just a quick thought... You can cut down on some of the gyros and accelerometers by going with a Memsic unit, as they can detect accelerations on two Axis, as well as tilt on two axis. Then, all you would need is a single axis gyro and/or compass, and a 1 axis (not sure if they make them?) accelerometer to get the last axis the Memsic unit doesn't cover.
  • Graham StablerGraham Stabler Posts: 2,507
    edited 2010-03-23 00:02
    Markaeric,

    The mensics only detect acceleration, gravity is an acceleration only a static one and this is how they measure tilt, the problem comes when you start to move, the sensors cannot tell the difference between gravity and acceleration due to movement. This is why you tend to have an accelerometer and gyro on balancing robots because the gyro just notices the rotations. You can certainly build this for RC with a 2-axis memsic and two single axis gyros, no need for one on Yaw as it will not be very sensitive like a normal heli I suspect but it might not hurt.

    Graham
  • markaericmarkaeric Posts: 282
    edited 2010-03-23 02:29
    Doh! I neglected to consider that, Graham. Thanks for the correction.
  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-23 04:08
    Great input. This will be a total learning curve for me having never done anything like it before. However, I want to include all the axises gyros, accelerometers & compasses so that if they are needed then I have them. Too late later to find you are missing an axis of something - the pcb is done. I only want to do the pcb once with all the options covered.
    If you buy a 9dof board then you have them all anyway and this seems to be the cheapest alternative to me building a pcb. All the individual modules available are an expensive way to build it. You will still need a prop board anyway, so for minimal extra cost I will have all the options covered. I will make the pcb available without the sensors so you can fit what you like and use the 9dof if you want.

    Gyros: I am thinking why use 2 different gyros like LPR530AL & LY530AL (or LPY530AL)? It makes more sense to use 2 x LPY530AL and just rotate the chip 90deg on the pcb. You have two X axis, but since one is rotated 90deg you have an X & Y, and ignore one of the Z axis. Same applies to 2 x IXZ500. Anyone know why not - I cannot see why not?

    As I said previously, I have been looking at using a cheaper MC9S08 16/20 pin micro to do the ADC from the gyros and send this to the prop (I2C or serial) 2 pins. It's only a collect and forward program. All processing will be done on the prop.

    I am about to start laying out a pcb, so any last minute suggestions/requests?

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  • Roy ElthamRoy Eltham Posts: 2,996
    edited 2010-03-23 07:53
    Cluso99, couldn't you just use a multi channel ADC with serial interface instead of using another MCU? Wouldn't it be cheaper? I guess part of the issue might be the number of channels of ADC you are going to need. For example the H48C had a 4 channel ADC on it which is used for reading voltage ref and the 3 different axis. I assume you need at least 3 more channels for gyro axis, and again at least 3 more for the compass axis, right? So 9-10 channels at least if not 12-13 if some/all the devices have voltage refs. Does the MCU you plan to use have that many ADC channels?
    Or is it the case that you only need ADC for the gyros and not the other stuff?

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  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-23 08:56
    Only need the ADC for the gyros as the other parts are I2C. I looked at ADC chips and they were more expensive than a cheap micro. I need a minimum of 5 channels, but 8-10 would be preferable so I can read the x1 and x4 or x4.5 inputs and the 4th duplicated axis too. The unreleased gyro is I2C and will not require a micro.

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    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
  • BuildThingsBuildThings Posts: 31
    edited 2010-03-23 13:06
    @Cluso

    I have been playing with the 9DOF for the last few nights and will be posting test data as soon as I make it look pretty (Today).

    After spending several hours reading some of the forums following other users of the 9DOF over at sparkfun and DIYDrones, I got to see how much work and testing those folks put into the AHRS code. It looks like they had some vibration issues on the first go around, but have overcome them. (Updated accelerometer output data rate to 50Hz (25Hz bandwidth) to avoid
    aliasing and increase vibration immunity)


    I have included the link to their code so everyone can get an idea of what functions are OBE to the board; also get an idea of what we have to write in Spin/PASM using the "raw" sensors.
    code.google.com/p/sf9domahrs/source/list
  • SzabiSzabi Posts: 58
    edited 2010-03-23 13:36
    Cluso,

    just as a last comment for the PCB. As I said I'm definitely beside a PIC. it's cheap and not complicate to use it as an ADC, but if there is enough space we could add 1-2 ADC's to the board layout. (not only to make Roy happy but to help other users wink.gif if somebody prefers using ADC's as an option).
    For a prototype board we should have all the possibilities we want. It would be nice but still I'm quiet sure this will not be the final layout smile.gif.... there will be so many surprises that we will have another 2 or 3 PCB versions I guess smilewinkgrin.gif
  • Roy ElthamRoy Eltham Posts: 2,996
    edited 2010-03-23 15:52
    Szabi, I don't care if it uses another MCU instead of an ADC, I only asked about that because I had figured an ADC chip would be cheaper than an MCU. Parallax sells an 8 channel 12bit ADC with SPI interface for $5.22 (or cheaper if you buy 10)... I guess I just didn't think you could get an MCU with 8 channels of ADC for less.

    I am a little concerned with issues like needing to buy other stuff to support a different MCU, like a programming interface/cable and other tools that might not be free. It depends on the the MCU, but if it has free tools and doesn't require another programming interface then it's not an issue. If it does require having to buy extra stuff beyond the MCU itself just to work with it, then it'll cost a lot more...

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  • Cluso99Cluso99 Posts: 18,066
    edited 2010-03-23 18:40
    BuildThings: Thanks for the link.·There is heaps of info here including the calculations. They have removed the HP filter from the gyros in the 9DOF pcb.

    I will take a look at the test data when you post it, although I am going to be busy for the next few days/week as I have to go interstate again.

    Szabi: I found the ADCs much more expensive than a micro. I am not intending to produce more than one pcb version. I don't usually require a second version although this time I am not as certain since there are analog parts on the board and this can complicate layout matters. I have only 1 version of TriBlade and RamBlade. I will not guarantee there will be no mods on the board, but if I can get a clean layout then there should be little problems.

    Roy: Providing we can keep the code simple for the micro - i.e. it only reads the data and sends it to the prop for processing, I could pre-program the micro. I do not have development kits for Atmega or Freescale, but I do have a PIC programmer (never used). However, the chips I am proposing (PIC and Freescale) have simple programming interfaces so hopefully we can use the prop (from another board perhaps) to do the programming incircuit. The micros I am looking at cost ~$2. I certainly do not want anyone having to buy another programmer as it blows the costs out of proportion and then we would be better using a ~$5 ADC. If possible, I want to bring in both the x1 & x4 gyro outputs per channel (plus Vref) to the micro.

    General:

    I am aiming at placing 2x LPY530AL XZ gyros and 2x IXZ500 XZ gyros on the pcb so we can use either brand gyros.

    The RC receiver input will be a 8x3 way 0.1" pin header. The ESC output will also be a 8x3 way 0.1" header. So 8 channels available.

    Question: Has anyone seen the interface for the RC & ESC's? I need to know (I haven't researched yet) if the input requires series resistors? I am presuming yes since the RC receiver is 5V. Likewise for driving the ESC's from the prop·do I need a level shifter to 5V? If anyone can provide me a link where this is discussed I would appreciate it.

    Testing:

    Aydin has a nice setup. I thought this would be a good start. Just place a motor on an arm with a hinge at the center. We should be able to drive the motor through the ESC from the prop and connect the prop through the serial port to the pc to control the motor.

    I had thought (and it would be the next phase) that I would tie a line (say only 1" to start with) to the center of the frame and let it take off by motor. Then by adjusting from the pc via the prop we could then get this to stabilise on the bench. No RC involved yet. This would make it cheaper for others to get it running on the bench without an RC unit and not complicate this section yet. (I have my RC gear).

    Once we can stabilise liftoff we can increase the line and let it fly higher. I still think we will input parameters serially from the pc using a terminal program. So we will give it keyboard commands like the arrows and shift-arrows to speed up or decrease the four motors. Ultimately I think we can fly this quad tethered in a garage by a keyboard. Once it is working rather well, we can add the RC unit. I am thinking of using bst as the compiler because it has an inbuilt terminal that switches automatically in after a successful download to the prop and it is pc platform independant (windoze, *nix & mac).

    Oh, I plan to use the serial on the prop that we will connect to the GPS later (in case you are wondering where the pins are coming from).

    Does this make sense???

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    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
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