Friday, 18 September 2015

Multi Rotor Part 2 - Quadcopter Construction - Step 2

Building a 550 mm Quad Copter using PVC pipes.
Materials required.
  1. Arrange or by round PVC pipe of 3/4" dia,  8 pcs T-joint 3/4",  4 pcs L joint 3/4" and one 4 way split joint 3/4".
  2. Get solvent cement used by plumbers for sealing and joining PVC pipes.
  3. Buy glues, Flex Quick (cyno based instant adhesive), Araldite ( standard epoxy adhesive), Fevicol (synthetic resin adhesive).
  4. Get 2 pcs of aluminium sheet of 1.5 to 2 mm thickness or 2 pcs of 5 mm poly carbonate sheet ( size 6*16 cm and 8*11 cm).
  5. Sufficient number of Cable ties.
  6. Nut and bolts as per the pipe diameter, small screws.
  7. Bullet connectors for joining ESC, Motor and battery.(minimum 22 pairs of 3.5 or 4 mm bullet connectors).
  8. 12 to 16 AWG Electric cable for making ESC connection harness (RED and BLACK).
  9. Colored tapes for marking and decorating frame.
  10. Velcro for attaching battery.
  11. A round or square transparent plastic container to make the dome.
  12. Spacers as required, made out of empty sketch pen shell.
  13. Cycle tube to make rubber pads for vibration dampening.
Electronics Required - (You can change the configuration as per your requirement)
1. BLDC outrunner motors - 04 nos.
  • I used motors with the following specifications, 
  • MOTOR TOP STAR - KV: 1000
  • Dimensions (mm):Φ22×10 - Weight (g): 47
  • Shaft Diameter (mm):Ф3 - Battery: 3×Li-Poly
  • No load current (11.1V): 0.6 A - No load RPM:11500
  • Load current (11.1V):11.6 A - Max Power(W):130
  • load RPM: 7196 - Test Thrust (g):620
  • Test prop:9 x 50", 10 x 4.5" 10 x 4.7"
2. ESCs - 04 nos.
  • I used ESCs with the following specifications,
  • IPEAKA 30 Amp
  • 2-4 LiPo - 5-12NiMh
  • BEC 5V 2 amp.
3. Propellers (2 clockwise-2 anticlockwise)- 04 nos.
  • I used 10 x 4.7 Slow Fly propellers.
4. LiPo Battery - 01
  • I used Zippy Flightmax 3000 mAh 30C 3S LiPo.
5. Flight Controller -01
  • I used KK 2.1.5 LCD Flight Controller.

  • The KK2.1.5 packing is new with updated sensors, memory and header pins.
  • The KK2.1.5 is next big evolution of the first generation KK flight control boards.
  • The KK2.1.5 was engineered from the ground up to bring multi-rotor flight to everyone, not just the experts.
  • The LCD screen and built in software makes install and setup easier than ever.
  • A host of multi-rotor craft types are pre-installed, simply select your craft type, check motor layout/propeller direction, calibrate your ESCs and radio and you’re ready to go!
  • All of which is done with easy to follow on screen prompts!
  • The original KK gyro system has been updated to an incredibly sensitive 6050 MPU system making this the most stable KK board ever and allowing for the addition of an auto-level function.
  • At the heart of the KK2.1.5 is an Atmel Mega644PA 8-bit AVR RISC-based microcontroller with 64k of memory.
  • An additional polarity protected header has been added for voltage detection, so no need for on-board soldering.
  • A handy piezo buzzer is also included for audio warning when activating and deactivating the board.
  • The KK2.1.5 added polarity protection to the voltage sense header and a fuse protected buzzer outputs, in case something is accidentally plugged in incorrectly.
  • The voltage sense line has been updated for better accuracy.
  • The board is clearly labeled and the voltage sense line color has been changed to red for easy identification, making installation and connections a snap.
  • If you’re new to multi-rotor flight or have been unsure about how to setup a KK board then the KK2.1.5 was built for you.
  • The 6 Pin USBasp AVR programming interface ensures future software updates will be quick and easy.
  • Specs:  Size: 50.5mm x 50.5mm x 12mm     Weight: 21 gram (Inc Piezo buzzer),          IC: Atmega644 PA     Gyro/Acc: 6050MPU InvenSense Inc.,  Auto-level: Yes        Input Voltage: 4.8-6.0V     AVR interface: standard 6 pin.      Signal from Receiver: 1520us (5 channels)      Signal to ESC: 1520us         Firmware Version: 1.6:             Pre-installed firmware. - Dualcopter,  Tricopter,  Y6,  Quadcopter +,  Quadcopter X,  Hexcopter +,  Hexcopter X,  Octocopter +,  Octocopter X,  X8 +,  X8 X,   H8,   H6,   V8,  V6,   Singlecopter 2M 2S,   Singlecopter 1M 4S,  (Custom Mix via the "Mixer Editor" option)
6. Tx-Rx -01
  • Avionic 6Ch Computer Tx-Rx.
Tools Required.
  • Hand drill or Power drill with drill bits.
  • Handsaw blade.
  • Screw driver set.
  • Knife.
  • A good quality plastic/wood/steel rule.
  • Soldering iron, solder wire and soldering paste.
  • Cutting pliers.
  • Ellen key set.
  • Nose pliers.
  • Marker pen.

550 mm PVC Quad Copter Design.

Frame -
  • For frame I chose round PVC pipes used for electrical wiring.
  • Sometime you can find waste pieces of this in a junk yard, make us
  • e of that.
  • If you can't manage then you can buy it from any local hardware shop.
  • Use a handsaw blade to cut the PVC pipes as per the dimensions given above.
  • To decide the arm length add the propeller size from the middle of the quad copter and that's where the motor will go.
  • Cut aluminium plate or poly carbonate sheet for Top and Bottom plates as per the dimensions given in the drawing.
  • That's all the cutting work you have to do.
Frame Assembly.
  • Dry fit all the PVC parts together as given below.
  • Do a measurement of the frame after dry fitting to match with your drawing.
  • Some adjustments will be required because when you insert the pvc pipe into T and L joints all may not go inside the same length.
  • Now do all required markings with a permanent marker pen.
  • Such as arm number, motor rotation direction, center of all outer T joints, center line from one end to other end, motor mount, etc..
  • Draw a line tip to tip through center on both arms, make sure that it meets exactly in center of round PVC union (if not do necessary adjustments).
  • Once again measure all four arm lengths from center and between arms, make sure that all measurements are same (less than +/- 5 mm tolerance can be given).
  • Equal length and spacing between the arms are most important because it directly affect the flight performance of your Quad.
  • Mar the center of outer T, motor mount center should go through this point.
  • Take the motor mount and mark out where you need to put the screws. This is one of the major things to do because even if one of the screws is a little off it can rattle the motor out completely.
  • Before drilling holes for mounting the motors, once again measure motor center to motor center and one arm to other arm and make sure that all measurements are equal.
  • Now you can drill holes.
  • Take the Top and bottom plates, place them on the frame and do the markings on the plates and pvc frame for drilling holes for fitment.
  • Now before taking the parts apart,  mark all the parts and their position for identification when you do the final assembly.
  • Any coding system which you can understand afterwards can be used.
  • We can do the covering the arms with color tapes after gluing the joints and drilling holes, otherwise all the markings will get covered.
  • The purpose of coloring the arms is to find out the orientation of your Quad Copter during flying and to give an attractive look.
  • If you are satisfied with the frame preparation, now you can start gluing it.
  • Gluing the joint can be done in two ways, you dismantle the entire frame and start gluing each joint from step one, or glue one by one joint without dismantling fully.
  • Method one will be more easy and accurate way to do it (provided you done proper markings on all parts).
  • In every step of gluing keep measuring the arm length and spacing. 
  • Maintain the direction and flatness of all T joints.
  • Opening of the 4 way union will face downwards.
  • You should do the gluing by keeping the frame on a flat surface.
  • Any adjustments required is to be done before the glue dries.
  • When you complete gluing of all joints your frame is ready.
Preparation of Electronic Parts.
  • We have to solder the bullet connectors to the motor and ESC wires.
  • Always connect female end to the supply side.( This is a safety precaution, naked male ends will cause shorting).
  • In this step you have to solder 20 pairs (05 pair for one set of motor and ESC).
  • For doing this, take a small wooden plank and drill two or three holes on it so that the connector sits in this hole freely.
  • Heat the connector with soldering iron tip and fill solder in the connector cavity, insert the wire into solder filled cavity and remove the soldering iron, cool it by blowing air.
  • Check the soldering by pulling it apart. If the wire comes out due to dry soldering repeat the process.
  • Next level is making the PDB/ harness. Now make 4 way harness using 12 to 18 AWG wire (select the wire gauge as per the ESC rating) to connect all 4 ESCs to battery. (you can use ready made Power Distribution Board if you want) 

  • On the ESCs side of the harness use female connector and battery side male connector.
  • For converting 4 wires to single one, solder the joint firmly by applying sufficient solder and insulate the joint using heat shrink tube or insulation tape.
  • The white and red thin wires soldered to the joint is for battery monitoring connection of LCD Flight Controller.
  • If your LiPo battery came with HT60 or any other type of connector then you should connect the same type of connector to single lead end of harness.
  • Check the prepared connections for correct polarity and color coding.
  • Important - All the joints and bullet connector should be properly insulated using heat shrink tubes or good quality insulation tape.
  • Shorting of wire may cause fire, melting of wires, explosion of LiPo battery and can permanently damage your electronics.
  • Before starting actual assembly connect the prepared electronic parts together and do a testing to make sure that  all are working properly and along with this testing you can also do the ESC calibration and programming.
  • Now you can start fitting the motors and ESCs to the assembled frame.
  • Connecting the ESCs
  • I attached my ESCs directly to the frame arms using zip ties with the power wires and signal wires running towards the center plates and the motor phase wires towards the motors. 
  • I connected the red and black power wires from each ESC to red and black power wire from my power harness.
  • I connected red to red and black to black to avoid shorting and ruining the ESC.
  • I used one zip tie on each side and placed the ESC on top of the frame arm so it can be cooled by the wash of the prop.
  • Motor Phase Wires - The order in which these wires are connected determines the rotation direction of the motor and prop.
  • Depending on the motor and ESC being used the wire colors may vary.
  • Initially you can connect the three motor wires with each ESC in any order. Later, you can switch any two of the three motor wires to reverse the direction of a motor to have correct direction of rotation.

  • While attaching the Motors you should pay proper attention to reduce vibration which is the number one enemy for flight control board.
  • I used soft rubber pads made out of cycle tubes as vibration dampener under the motor mounting.
  • Motor and propeller adapter should be well balanced, never use motors which are damaged or having bend shaft.

  • I arranged the power harness between the two center plates and inside the round cavity of four way spliter.
  • Connection wires for battery coming through the bottom center plate where my battery can easily connect to it when attached.
  • ESC wires are routed to bottom side through the holes made on top center plate , ESCs and secured to the arm with zip ties.

  • Next I attached the flight control board on the top plate.
  • I attached the KK2.1.5 flight controller to the top plate using the soft casing that came with the board. This will act as a vibration damper.
  • And then a cover for the protection of Flt Control board ( This protection case can be made out of any light weight food pack or plastic box).

  • Some of the things in the center can range from the ESC or ESc wires, RC reciever, control board, and the battery.
  • The center plate size and design all depends on how you want to space out and arrange your aircraft.
  • For my design I used Velcro on the bottom plate to hold the battery attached to the frame.
  • Be sure to have some gap between frame and plates when you attach the top and bottom center plate of the quad to the arms to accommodate all the wires..
  • You can use spacers made out of any thin plastic tube (I used empty sketch pen shells to make spacers).
  • After proper arranging of all the wires, attach the top and bottom plates to the frame, use spacers to maintain required gap.

  • Battery Elimination Circuit(BEC) & Signal Connector.
  • Connect the BEC power and signal wires to the flight control board as per the sequence mentioned for X or + configuration.
  • I selected the X configuration.
  • For each motor, I connected the ESC BEC/Signal connector to its matching flight control board connector.
  • You can see from the picture below  that my ESC BEC/Signal wires are Black , Red and White. 
  • Black is the ground, red is power, and white is the signal wire.
  • Many other ESC BEC/Signal wires are broen, red, and orange where brown is the ground, red is power and orange is the signal wire.
  • Most flight control board manuals suggest only connecting one BEC power wires from one ESC to the flight control board.
  • A board only needs one power source and multiple power and ground wires can cause problems.
  • The easy fix for this is to just remove the power wire of 3 other ESC at the connector end and insulate it.
  • The KK2.1.5 is unique in that only the first motor connection supplies power to the board. So, it should not be a problem if all of the ESCs power and ground wires are connected.

  • Attaching & Connecting the Receiver
  • I attached the receiver to the front of top center plate using some double sided foam tape.
  • I used receiver connection leads to connect the receiver to the flight controller.
  • The Avionic 6 channel TX/RX connector labels mean the following:
             CH1 = Aileron
             CH2 = Elevator
             CH3 = Throttle
             CH4 = Rudder
             CH5 = Aux 1
             CH6 = Aux2
  • Each connector has three pins. One for the signal, one for power and one for a ground.
  • The pins on the inside are the signals, the middle pins are for power and the outer pins are the grounds.
  • The receiver gets its power from the flight control board and only needs one power and ground wire connected.
  • You can see I connected all three pins on the aileron channel to provide power to the receiver. Since the other channels only need to carry a signal, I used single connector to connect the signal pins of the elevator, throttle, and rudder.
  • Finally, I placed the cover over top center plate. It fits nicely, protecting the flight control board.

  • Securing the Props
  • This X configuration quad copter requires two clockwise(CW) rotating props and two counter-clockwise(CCW) rotating props.
  • I attached the props to the motors using the collect type prop adapters that came with the motors as pictured above.
  • I used one of the plastic adapter rings that came with the props to match the size of the collect adapter.
  • The plastic ring fits inside the center of the prop. After placing the prop onto the collect adapter, I tightened it down with the bullet shaped nut.
  • Now you completed the build part of your Quad Copter.
  • This is not so heavy and easy to fly, low cost and rigid.
  • Also, it has a nice landing gear and protective cover for the electronics.
  • It is very stable and fun to fly around, but it is not a super lightweight frame designed to do acrobatic flying.
  • To do more serious heavy lifting would involve spending more money on bigger low kv motors, bigger stronger props, more sophisticated flight controllers and radios and a more stronger frame, Of course, it could be upgraded.
  • Additional Facilities.
  • Now that you have finished your quad build you can feel free to add whatever you want to it. 
  • Maybe, a camera, LEDs, speakers, anything that you can carry and want to fly!
  • Add-on weight should not be too much so that your flight time reduces or will become difficult to maneuver.
Next : Step 3
  1. Setting up and Turning The KK 2.1.5 LCD Flight Controller.
  2. Flight Testing.

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