Step 20Landing Skid
It is impossible to attach the landing skid if the bottom plate is already attached to the top plate. Take the black landing legs and place them into the thin slots in the top plate. These slots should be next to the left and right arms. Align the hole and then use some screws and nuts to secure them.
There should be some thin black cross-members for the legs in your kit. Some people glue these in place but I used electrical tape.
The actual skid piece goes on the bottom of the legs, it has slots so it stays in place but they still tend to fall off very easily. I've used electrical tape to secure them.
Step 21Bottom Plate
I made two aluminum strips which will mount onto the bottom plate. The attached pictures show you the dimensions of these stripes.
Some double-sided velcro straps are glued to one of the aluminum strips with epoxy glue.
The aluminum strips are screwed to the bottom plate, using a nut as a spacer. These pieces will make it easy to strap in the battery later.
Place the power distribution "spider" between the top and bottom plate before you join the two plates. Arrange the wires in a neat fashion first.
Join the two plates using the stand-offs, nuts, and screws.
Step 22Mount the Circuit Board
Before the top dome can be placed, the circuit should be mounted first. Do so using the short stand-offs and screws. You might want to use washers with your screws. The screws might also need to be cut to a length such that it can fit into the stand-offs.
The circuit board should have a direction indicator, make sure it is pointed in the right direction.
Step 23Top Dome
There are 8 dome support pieces, 4 cross-members, and 2 top pieces in the frame kit.
The support pieces attaches to the sides of each arm. Use the screws and nuts to secure them. The screws will need to be cut as the width of the arm is too narrow for two full length screws.
Some of these are grey to indicate those are the pieces which should face forward. Attach those to the front arm.
The cross-members goes between two support pieces. The two top plates will sandwich all the support pieces. Use screws and nuts to clamp down on both top plates. Notice that it is very easy to over-tighten these particular screws due to the gap between the two plates.You will risk cracking the plates if you over-tighten.
I've also attached some velcro tape to my RC radio receiver and the dome to make it easy to mount and dismount.
Step 24Mounting Motors
Each brushless motor can be mounted to an arm. Use 1/2" long #4-40 machine screws (please use steel) along with nuts, flat washers, and spring-locking washers. Make sure these screws are very tight.
When you are ready, mount the propellers. Follow the rotor spin direction diagram that I've provided.
The motor should have arrived with all the hardware you need in order to mount the propellers. There is a cone shaped washer, make sure that piece goes between the nut and propeller, and that the cone is facing the propeller. The cone shape is what keeps the propeller dead center on the shaft (if it's not centered, it will vibrate from the imbalanced centripetal forces).
Step 25Final Wiring
Plug the motors into the ESCs. Do not care about the order of the three wires for now. We'll a test later, if they spin the wrong way, we'll fix it then.
Plug the ESCs into the power distribution "spider", watch your polarities.
Plug the servo cables from each ESC into the flight controller circuit. The appropriate location for each ESC should be indicated on the PCB.
Channel 1 to 6 on the RC radio receiver must go into the respective RC signal input of the flight controller. Make sure that the RC radio receiver is powered by 5V from the flight controller somehow.
Please be careful, do not plug in anything backwards. The PCB should be clearly labelled with the direction in which the servo wires should be plug into.
If you are using my circuit design, please follow the appropriate wiki article for even more details.
Step 26Software Setup
In the "preparing the microcontroller" step, you should already have the bootloader installed onto the microcontroller and Arduino IDE completely ready to compile for the ATmega644P.
Connect your FTDI cable (or similar USB-to-serial cable) to the circuit board.
Attached here is a modified version of AeroQuad V2.4.1 flight software. I have modified it to work with my circuit design. Download it, open it with Arduino IDE, compile it, and upload it to the circuit board.
Also please download and install the AeroQuad Configurator(version 2.7.1 is what I'm using).
Below is just a small summary of what you need to do with the AeroQuad Configurator. Please follow theofficial instructions for AeroQuad Configurator for more detailed instructions.
Use the configurator to talk with the circuit, just make sure it works first. Then run through the steps to initialize the EEPROM. Run the sensor calibration with the help of a spirit/bubble level. Make sure that the sensors respond correctly. Make sure the RC radio receiver PWM signals are being read correctly.
Calibrate the ESCs by following the instructions in the configurator (basically power off the ESCs, click an OK button on the screen, power on the ESCs, click another OK button). You can then make sure the motors spin in the correct direction (do this without the propellers for safety reasons)
Step 27RC Controls
Your RC radio transmitter has two joysticks for the first 4 channels. I have attached an image to show you my radio and which joystick direction corresponds to which channel (the arrows indicate direction of increasing pulse width). Your radio might be different, but they should be labelled
Usually one joystick controls throttle and yaw, and the other stick controls roll and pitch.
Depending on whether you are left or right handed, you may wish to control throttle & yaw using the left or right stick. To make this change, simply swap the signal wires between the flight controller circuit and the RC radio receiver.
If a direction is reversed, the RC radio transmitter should have a built in reversing setting. If it doesn't, you must have the worst radio in the world and should probably buy a new radio, or else, find the source code that takes the signal inputs and flip the values. (or you can disassemble your radio and re-wire the joystick's potentiometers).
Also the joysticks are usually spring loaded so that they return to center when you let go. You probably do not want this for the throttle. Please see your RC radio transmitter's manual to see how the spring can be disabled. On my RC radio transmitter, I simply take it apart and remove the spring (don't lose it!).
The flight software (AeroQuad) have an ARMED and DISARMED state, in the disarmed state, the motors are disabled for safety. Move the throttle down and then to the left to disarm. Move the throttle down and then to the right to arm. Memorize this so you can disable the motors in an emergency. On my circuit board design and modified version of AeroQuad, the LED3 indicates that the motors are armed.
The switch on channel 5 switches the software between the "acrobatic" mode and the "stable/attitude" mode in the software.
Step 28Tuning and Calibration
Charge and strap in your battery. You must learn to ARM and DISARM your helicopter first, get good at this since you must disarm your helicopter as soon as something goes wrong. For the AeroQuad software, to ARM and DISARM, lower the throttle joystick to the bottom, and the move it left for DISARM and right for ARM. With my circuit and modified software, LED3 being lit means the helicopter is ARMED.
This should be the first time when you have your motors running. Make sure you always have a good solid hold on the frame such that you will not be harmed by the spinning propellers. Also wear eye protection! Tuning is best done with two people, one person to hold the RC radio transmitter, and the other person to hold the helicopter.
First, read this: Pre-Flight Checkout List
Turn on the helicopter with the propellers installed. Run the configurator to calibrate all the ESCs (follow the provided official instructions). Make sure they spin according to the rotor spin direction diagram. If a motor needs to be reversed, then recall what I said about swapping the wires between the ESC and the motor.
There are several parameters that you can tune.
The transmit factor is there to adjust the sensitivity of your RC radio transmitter. This value depends on your personal piloting skills and preference. The smoothing factors are the constants for low-pass-filtering the RC PWM signals, leave them at the default values unless your transmitter is very noisy.
Perform a sanity test by using default values. Raising the throttle should move all 4 motors faster. Trying to yaw will cause two motors which spin in the same direction will spin faster than the other two. Trying to pitch or roll will cause opposing motors to spin at different speeds. You should be able to feel the forces with your hand that is holding the helicopter. Also use your hand to introduce forces, and the helicopter should respond by applying counteracting forces appropriately. If something doesn't make sense, a value is probably reversed/negative in the software, use the configurator to identify it and correct it in the Arduino sketch.
You can also adjust the PID constants to suit your airframe. Start off with the default values. The P term is adjusted first, try and rotate the helicopter by hand while it is flying, raise the P value until the helicopter resists your hand very well, but lower it if the helicopter oscillates. Do this for all three axis.
AeroQuad's documentation do not suggest you adjust the I term for acrobatic mode. It also says "A negative D value is used to help the AeroQuad change faster to a level position after forward flight. It is possible to leave D = 0 and still see attitude flight. Using a negative D value is only needed based on user preference."
My summarized version about PID tuning is really short, for more detail, please see:
Also see the official AeroQuad Configurator documentation for more details about tuning stuff.
Step 29Flying
Now that everything is tuned, you should be ready to fly! Since you already tuned the helicopter, you should already be familiar with how to control the helicopter. Charge up and strap in your battery and go to your airspace.
Make sure you stand far away from the helicopter. Wear eye protection. The propellers are really dangerous. Do not attempt to "hand launch" the helicopter, just in case it wants to slice your neck as soon as you let go.
Try to fly outdoors during no wind conditions. If you want to fly indoors, then find a large room because the downwash air from the helicpter would cause too much disturbance in a small room.
Buy plenty of spare propellers, which break the fastest. Also, the frame from HobbyKing isn't very durable since it's made from plywood, but since each frame kit is $15 and comes with 4 arms, you should buy extras since arms break fast.
Watch your battery monitor while flying. When any three of the cells in your battery pack becomes drained below the safe threshold, you must try to land immediately, or else you will damage your battery.
Related Reading:
- Beginning Flight Tips - AeroQuad Wiki
Step 30Repair, Re-tune, Recharge
If you crashed while flying, you might have broken some of the quadcopter's arms. There's no easy way to fix this, so just disassemble the frame and replace the arm with a spare.
After crashing, check if the battery is damaged. A damaged lithium polymer battery can explode! Immediately after the crash, disconnect the battery immediately if it has not exploded already, and inspect it before judging whether or not you can keep using it. If it's dented, bulging, bent, punctured, or cut, then dispose of it properly.
Broken propellers are easy to replace, but make sure that the shaft or motor isn't damaged. Remove the propeller first, then run the motor at a low speed to see if it's still functioning and not wobbly. If it's wobbly, then you should replace the motor, do this while not flying, or else you risk having the motor fail in mid-air which is more dangerous.
If you don't like the flight characteristics, just reconnect your flight controller back to your computer and re-tune the parameters until you are satisfied.
If you've noticed that your quadcopter doesn't stay stable no matter how hard you tune the configuration parameters, then maybe the airframe is vibrating too much for the sensors to be effective. Vibration is caused by imbalance of mass around the spinning motors. When the mass is balanced, the net centripetal force around the motor is 0. When there's an imbalance, then the centripetal force will have a magnitude greater than 0 and the angle of that force will spin. This becomes oscillation, which is vibration. So to eliminate vibration, we need to apply a force equal in magnitude but opposite in direction. Get two zip-ties per motor, and tie two zip-ties around each motor. While the propellers are installed, move the zip-ties around until the force they introduce cancels out the vibration.
Recharging the battery should sound straight forward. My charger is pretty nice and full of features, but it didn't come with a manual (I found one online later). There are two main power wires (positive and negative) that connects from the battery's main wires (the thick ones) to the charger (two banana plug jacks), connect those in the correct orientation. Then plug the JST balance connector from the battery to the balancer jack of the charger. One characteristic of lithium polymer batteries is that each cell must be monitored and balanced with other cells during charging, hence why your battery has 2 different connectors.
Place the battery into a Li-Po bag (it's a fire-proof bag you can buy that's designed for charging lithium polymer batteries), or put them into a cooking pot like me. On the charger, select the lithium polymer charging routine, set the number of cells to 3, and start the charge cycle. The process should be automatic but you should not leave the battery un-attended during charging.
If the charger can charge at 6 amps, then get a power supply that can handle 6 amps (I use a laptop power adapter). Most ordinary wall adapters cannot handle that much current, do not make that mistake.
Please charge at 1C or less, this means if the battery is 5000 mAH, then you can charge at 5 amps, but if it's 2200 mAH, then you can charge at 2.2 amps. Maximum Current divided by Battery Capacity equals C rating. For more info, read this guide on lithium batteries.
Step 31Final Thoughts
You can also experiment with flight software based on MultiWiiCopter, which is very similar to AeroQuad. MultiWiiCopter supports more airframe configurations such as tri-rotor, hex-rotor, and octo-rotor. Its graphical user interface is also different (based on Processing.org, which is Java, I like it better than the LabView based AeroQuad Configurator).
To take flight videos, I spent $5 on a keychain video camera like this one. They are cheap and lightweight. Do not use velcro to mount the camera since the vibrations will ruin the video, use tape instead.
The frame kit comes with a camera attachment, you can attach a small servo to it, but I didn't use it. Also, apparently this helicopter landing skid is a good match for the frame.
My instructable focuses on + configuration flying, but you can easily convert your quadcopter to fly in X configuration. It requires some reconfiguration and recompiling of the source code. The circuit board needs to be mounted at 45 degrees. The landing skid needs to be re-mounted at 45 degrees (the frame kits have slots and mount pieces already for X configuration mounting).
You probably have seen two of my flight controller circuit designs. My designs usually allow you to add in magnetic compass sensors and barometric air pressure sensors. These sensors can be used to let your software get heading and altitude data, which can aid in keeping the quadcopter facing one direction and stay at one altitude. GPS can also be added. The combination of these extra sensors can help with autopilot capabilities. AeroQuad code and MultiWiiCopter code both have some support for these sensors.
