Sunday, 20 September 2015

How to build a quad copter. All the info you need.

How to make a quad copter 

  • This paper is trying to cover the construction of a quad-copter starting from 0 knowledge about it. 
  • This paper covers step by step instructions for ardu-copter build using eBay purchased parts. 
  • Requires minimal knowledge of soldering and electrical. 

1.0 Background

Any copter major components are:
  1. Remote Transmitter and Receiver, 
  2. Model/Flight Controller
  3. Sensors
  4. Electronic Speed Control (ESC)  for motors.
  5. Motors.
When you buy the Transmitter (a 7, 8 or 9 channels) it would come with the receiver module as well.  The devices have a pairing procedure described in the  accompanied instructions. The Device you keep in hand is the transmitter (TX) and the receiver (RX) is placed on the model (copter/car/boat). Pairing means that the RX would receive radio waves only from it's paired TX . If they are not shipped together the RX and TX have to be paired manually. There are RX'ex which supports pairing with a wide set of TX-ex, and vice versa. The pairing procedure is usually specified in the TX and RX manuals. For a modern RC as Boat, Plane, Auto-mobile, Quadcopter you can browse There is a variety of brands can be chosen from. The new generation RX & TX are all digital and computerised. The TX has a complicated menu for setting up each channel and to associate channels to knobs. The manual is a usually a nightmare, especially if they came in chineinglish would be much worst than my article.
On the TX, usually each knob or switch is associated to a separate channel. The TX's, is sending commands over these channels to RX. On the RX there are  several output pins, usually one per channel. The RX is connected with the flight controller over several channels. The logic between user intend and copter
sensors is performed in the controller. The result of signal processing  ( user intend + sensor-data -> outputs) is delivered to the output pins. For a quad copter we will use 4 outputs. For a hexcopter we would use 6 pins, and for a octocopter, all eight outputs. The output signal is amplified then by motors voltage/current amplifiers. They are called ESC. ESC stands for Electronic Speed Controller. The last generation ESC are smart modules which run  firmware software as well. They processes the output from the controller and provide to the motors right waveform for spinning them up. The ESC can be programmed by a precise sequences of input levels (up/downs) to target a wide range of batteries and motors. The servos or motors are the final components of the craft. They transform the electric energy to mechanical energy.

Remote Control  

Almost any remote with at least 6 channels  (can send 6 different commands at the same time) designed for RC model working in PWM (Pulse wave modulation). The remote is shipped usually with it's receiver (RX) module. To take advantage of al ardu-copter features the remote should have at least 6 channels. What are channels. The channels are like on the TV, independent transport pipes over the 2.4-2.5 Ghz. The Transmitter knobs (TX) can be assigned to any channel pragmatically from the TX menu set up options. Each decent TX transmitter has this kind of Set-up. This time we choose Turnigy 9X, 9 channels remote. which is s decent remote.
eBay search: Turnigy 9X, 9

Flight Controller

APM 2.6 Flight controller. FC is a micro computer. It has additional sensors for: atmospheric pressure to sense the altitude, accelerometer, to sense the acceleration and position, compass to senses the direction relative to earth and GPS. Some sensors are soldered on the same board with the microprocessor and some are external. The APM we buy has external compass and GPS. The other sensors are on-board. Compass and GPS usually are mounted on a separate
module (GPS+COPMPAS) same board and they are connected to the Flight Controller by I2C data bus. I2C data bus is a 2 wire serial protocol where multiple peripherals share same physical wires. For a basic stabilisation simple mode, the flight controller takes inputs from RX-remote and accelerometer. It
process the User Input + the internal accelerometer (keeping the quad horizontally) and applies a set of rules using PID's on each axis to full fill and act towards intended target. For other flight modes as we would see  MAP, GPS and or COMPASS should work flawless.
 eBay search: APM 2.6  (If is chinesse never flash it with versions after 2.6)

Motors and ESC,

Any suitable for the current and size of the copter. The motors are Step by Step electric motors with 3 phases and multiple pools (usually 12). The motors for high velocity spins are brush-less. ESC stands for Electronic Speed controller. All modern ESC contains microchips and can be programmed to target different types of motors, different type of loads, start stop, currents and so on. The ESC takes PWM (pulse variable modulation wave form) from Flight controller, pre-process it for the motor it was programmed , amplify it's to the current and motor voltage levels and apply it to the 3 phase motors.

Prerequisites & Tools

  1. Soldering station or solder pen.
    1. Soldering solder and rosin
  2. Screw driver with various set of heads and pliers.
  3. Screws
  4. Exterior double sided tape (Home Depot)
  5. 5V, over 500mA stabilised power supply.
  6. Digital/Analogue Multimeter.
  7. Aluminium Tape
  8. Cigarette lighter 
  9. Heat shrink tubing of different diameters


Note: Some eBay sellers might be outdated.  ()

  • ArduPilot Mega APM2.6 + NEO 7N High Quality GPS..Fisher­hobby..$89
    • with OSD and power module 
  • 1 x Quattro SKY III 30Ax4.................. gadgetinfinite....$34 
    • or
  • 1 x Hobbywing Skywalker Quattro 20 A ESC..gadgetextreme... $35
  • 4 x Sunnysky X2212 980 KV brush­less motors...flying­xsys......$74
  • 1x Metallic folding X frame,­mart.......$20
  • 1x Turnigy 9ch TX remote (v2) with RX..........ddosoff..........$75
  • 2 x Lipo 3S 2.2AH  or 2.6 Lipo Battery..........theaterpopcorn...$20
  • IMAX LiPro Balance Charger..................onlytop888. .....$23
  • 10x4.5 Propellers 6 x CW 6 x CCW..........TOMTOPUSA........$10 
    • buy  6,  they break 100% in few flights
  • New Carbon Fiber Balancer...................gagaoutleteb.....$6
  • Female to female jumper cables........maaqii.................$3
  • Connector 3mm Gold Plated Male and Female Bullet Banana
    •  ...................................... blacksmithproducts...$17
  • Pair Male and Female T Plug Connectors For Deans RC Lipo Battery
    • for helicopter......------.......................alline*a*t.......... $1
  • Outdoor double sided tape..............The Home Depot..........$1
  • Heat Shrink Tubing.....................smttrade05/sayal......$6

Block Diagram 

All components are pretty much connected together as shown.

The APM controller is connected to RX with few female to female jump wires. The power to RX is taken form the APM power line. The GPS+COMPASS module is connected to dedicated connectors to APM board. The Power module is connected to the APM board. The board takes the 5V from the power module. The APM also monitors the current and voltage of the system trough the power module. The 4x1 ESC (Electronic Speed Controller) is connected to the APM to it's outputs. The ESC's module provides 5V power to the APM on the output rails. This power does not interfere with the power given by the power module because there are 2 separate rows of power on the APM. Several add-ons as gimbal, optical flow, FPV and or cameras can be powered from either 2 lines of power form the module.

Turnigy Transmitter Setup

Turnigy proper function is required during APM construction. This is not a simple procedure and requires to know the remote pretty well. Try browsing the Turnigy manual for 5 minutes or so.

Different releases of the Remote software might have different menu structure In such case try to find the option by it's name, or look it up in the manual.

 Program ACRO Mode
   Start from Main Menu
     Press MENU, MENU to get to SYSTEM SETTINGS
       ◦ From SYSTEM SETINGS press DOWN, DOWN to get to TYPE SELECT
        ▪ From TYPE SELECT selection press MENU, to get to TYPE sub-menu.
         ▪ You see now 3 options, HELY, ACRO, GRID
          ▪ Press UP/ DOWN to select ACRO, then press MENU to get back
           to SYSTEM SETTINGS then EXIT to get back to MENU

 Program reversed Throttle
   Start from Main Menu
     Press MENU, MENU to get to SYSTEM SETTINGS
        ▪ Press MENU to get to STICK sub-menu
          From STICK sub-menu press UP/DN to select MODE2
           Press MENU, and when TRO REVERSE ?
           If you press MENU will reverse the THROTTLE. This option is a bit
          confusing, and you have to check it later on with the Flight software.
         Just remember how to get here.
        ▪ Press MENU MENU

 Program Reverse Pitch
   Start from Main Menu
        Press MENU to FUNC SETTINGS 1⁄2
          In FUNC SETTINGS1/2 select REVERSE
          ◦ In REVERSE Select ELE, then with +/- buttons will see
           WHITE BLACK and the ELE selection will be on the left bottom corner
          select REV, then
         ◦ EXIT
           ▪ EXIT
            ◦ Main Menu TUR. The pitch will be reversed. Will come over to this when we will have it all  connected.

    *** The second part of Turnigy programming is covered in section 6 ***

Pairing TX to RX

  • Required tools 
    • Pliers, 
    • Soldering iron
    • Heat-Shrink tubing
    • 5V stabilised power supply. 
On the 5 v power supply we cut the original connector and we solder a 3-wire of
female-female jumper cable as shown.

You should have couple of those from the ESC purchase packaging. Using the
multimeter,  make sure the +5V goes to the RED wire is connected to the middle pin.

Turnigy RX pin schematic is: (In the picture the RX module faces with It's LOGO upward)

Connect one female-female jump wire or the pairing Turnigy loop wire supplied with the package in the last row on the right of the RX. Power the RX to any other row from the 5V supply. The black wire (Ground) will go to bottom line of pins. The red wire to middle. Do not invert polarity, or power the outputs (top row). Wrong polarity would damage the RX.

Once powered,  the internal LED should blink.

Turn over the TX Remote and hold down the mid button, then with the other hand turn the remote ON.

The TX LED should stop blinking. The remote TX and RX are paired.

ESC 4x1 Calibration and setup

Schematic for ESC calibration step 1.

If the motors did not came with the banana male already soldered, solder to each motor the 3 mm male banana. Make sure you heat shrink each banana.

On the 4x1 ESC for each motors solder the female banana to all 12 black wires. Make sure you put the Heat shrink tubing up to the female ends. Also check the male and female motor connectors when coupled leave no gap between the heat srink insulators. On the power supply wires solder the Power module. Mostly the PM power output is towards the multi-wire connector (I2C thin wires), but you have to double check that

Solder also the LIPO T Plug female battery connector to the ESC power, and the male to the Power Module. Solder the transversal to the red wire (+) and the other (-), longitudinal connector to the black wire (ground or minus).
After having all the above soldered, connect the motors to the ESC. The wiring order does not matter for now. Just be sure you connect each motor 3 wires to 3 grouped wires to the ESC. Do not install any propellers. Connect motors. Don't power the battery to the power module to power the ESC without the motors hooked up.
At this stage yout circuit should look like the initial schematic, without the battery.

to be continued....




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