|Dec 26, 2013, 11:48 PM|
The Flying Eye
Shopping list and build instructions for a flying micro camcorder on a budget (airborn parts: $120), capable of shooting smooth and stable HD video. Its about the size of your eye plus propellers..
You are most welcome to post your question or suggestions into this thread, but dont be offended when I work the answers into the first page and delete your posts to keep all info concise.
The complete set as pitured, including two complete copter+cam, charger, balancer, scale, card reader and case, is worth around $650 in parts plus shipping.
|Dec 27, 2013, 04:09 AM|
frame and board: HobbyKing Pocket Quad
The pocket quad is one of the smallest Arduino boards available. It can run MultiWii, an opensource project providing a lot more configuration options that most other micro quad flight controller boards. Smooth camera flights require different stabilisation settings than the typical micro RTF quad, which is not programmable at all in most cases.
In MultiWii, control loop settings and processing of sensor values can be configured in detail. The IMU6050 on the pocket quad is likely to be a more capable sensor board than used on most RTF micro quads.
In addition, the pocket quad PCB doubles as frame, that saves some dollars for carbon booms and other parts.
The Pocket Quad is sold exclusively at HobbyKing, and costs somewhere close to $50. If you can snap up a buddy code (some buyers receive a buddy code for an item when checking out theirs), you can get it for ~$43.
The stock hardware (motors and props), the manual and the stock firmware have a lot to improve on. To get this quad flying properly, you should at least replace motors and props and upload a community approved software.
Most of what you possibly want to know about the Pocket Quad is or will be answered in this thread.
|Dec 27, 2013, 04:17 AM|
propellers: Hubsan X4
They provide the most thrust of all suitable props, and they require little to no balancing out of the box. On the downside, they are quite fragile.
You can get them at Banggood, I usually buy 10 sets of 4, that brings the price down to $1.37 per set, incl shipping.
There is further info on different props for 1mm shafts in this post.
|Dec 27, 2013, 04:57 AM|
Turnigy nano-tech 300mah 45-90C batteries
Carrying a camera is already a big task for such a small frame, lets keep the battery as light as possible. The 300mah 45-90C nano-techs have the most power in the sub-10g class to date (end 2013), and HK sells them for less than $3 (or less than $1 if you are in Australia).
I do the following to get the most out of these cells:
I set a counter on the transmitter: Without payload to 4:30min, with ~10g camera: 3:00min. I want the remaining voltage to be 3.7-3.8V. There is still a decent amount of lift available at that voltage, but a drop in performance is noticeable, and recover maneuvers are getting more difficult.
3.7-3.8V is a safe storage voltage, so I dont need to charge packs after flying, potentially for weeks.
If all packs from a flying session are discharged to the same voltage, they can be parallel charged at the same time without prior balancing.
Store them at 3.7-3.8V. Storing LiPos fully charged (4.2V) or fully discharged (3.0V) can shorten their life.
I made a habit of storing the majority of my packs at 3.7V, and only have a few ready to fly. When I then start flying, I put more packs on charge.
If you care about your batteries, throw away those USP-LiPo chargers. They are bad! Get a quality charger!
requirements to charge 8 300mah flight packs in parrellel at 2C: (1S) 3.7V, 4.8A
requirements to charge the 9XR battery pack at 1C: 3S (11.1V), 2.2A
Most hobby chargers will do that, you dont need to get a high end one.
I am using a Duratrax ICE for charging my batteries. Its not charging them better than any other good charger, but it has the following advantages:
- up to 10A discharge rate (the whole housing is a massive heatsink). I use this a lot to test battery packs. The charger shows the voltage to what each pack a battery drops when drawing the given current, and it measures the discharged mah. Very useful to weed out bad batteries. Some of these 1S packs dont last long. Battery testing = more consistent flight experience.
- a motor test program. This basically applies a given voltage to the outputs, and displays the drawn current. This is very useful to test and weed out bad motors.
Charge them as slow as possible! 1C is usually a very conservative charge rate. If you have a 1Ah battery pack, a 1C charger rate is 1A. The 300mah 45C's are rated at 2C max charge, e.g. 0.6A
I prefer to charge them at no more than 1C, e.g. 0.3A. A 1C charge from 3.7V to full takes about an hour. To have a non-stop battery supply, I use a parallel charging adapter for 8 battery packs.
8x300mah, that is a total capacity of 2400mah. 2.4A charge current corresponds to 1C.
With 2 sets of 8 packs, you can get a constant supply of 8 packs per hour with a conservative 1C charge rate. You can safely double the rate. However, if you plan ahead, charge your packs gentler and they will last longer.
Maker sure all packs have the same voltage when connecting them to the parallel charging lead. Connecting packs with big voltage differences might damage them. I havent seen problem when connecting pack with +-0.1V.
I use an adapter to connect 6 single cell packs to a 6S balancer. This allows a quick voltage check for multiple packs, but also pre-charge-balancing if needed.
|Dec 27, 2013, 05:08 AM|
motors: Chaoli CL-0720
Better motors mean more power and longer runtimes. No shop offered what I wanted, so I went digging at the source, and decided to divert the stream of goodies to my fellow propellerheads. You can get the CL-0720 motors at micro-motor-warehouse.com.
The motors come without connectors, you can either solder directly to the board or fit you own connectors.
To maximise performance and life span, dont run them in reverse!
Motor rotation and correct polarity is indicated by the wire color:
clockwise: red +, blue -
counter clockwise: white +, black -
Link to reviews and comparison to other micro motors on rcgroups:
1s micro/mini brushed quadcopter specifications and performance data
there are a few things you can do to extend the life time of your motors:
- dont stall them! Just 1 second of full power applied to a blocked motor can burn it out.
- dont run them too hot! If its too hot to touch, its too hot.
- dont run them in reverse! Rotation is typically indicated through the wire color. The best performance and life time is achieved by running the motors in their intended direction only. However, if you started running a motor in reverse for a while, dont reverse it, thats even worse.
- dont crash them! I know you will do anyway, and then usually one of the following happens: shaft bends, can dents, or end cap pops off. If the shaft or can is deformed, there is little you can do to rescue this one. There will always be a lot of vibration and lesser performance left. If the end cap pops off, turn the prop slowly in the "right" direction, and push the cap back on. A few motors survive that, but chances are the brushes are damaged after a cap pop.
If you observe any strange flight behaviour, it can be quite difficult to isolate in-flight if a motor is at fault. Also holding the quad and dropping each corner doesnt always give it away.
The most reliable way I found to check motors is to put them on a thrust scale and run them for a few seconds. If they are good, they make a consistent noise and produce a consistent amount of thrust.
If they get weak or wobbly, I throw them out.
|Dec 27, 2013, 05:17 AM|
transmitter: Turnigy 9XR
To calm down a twitchy micro quad for smooth camera flights, a programmable transmitter with custom curves helps a lot. There are many options out there, but the Turnigy 9XR's bang to buck ratio is hard to beat with OpenTX support and $50 price tag.
You can buy it at Hobbyking, but be aware that you have to buy Tx module and battery separately.
What I find a great help for copter flying, is a self centering throttle stick. You might be able to add a spring to the existing gimbal, or buy one for $5 and just swap them out.
|Dec 27, 2013, 05:41 AM|
camera: 808 #16 v2, D lens
808 #16 is producing HD (720p) resolution and resonable picture quality, and is still light enough to be lifter by a 10cm quad.
The D lens has a field of view of 120˚. It has some fish eye distortion, but the wide viewing angle make it easier to keep objects in the frame, esp. when flying line of sight.
Here is a lot of info about the 808 cams: http://www.chucklohr.com/808/index.shtml
Here is the rcgroups thread for the 808 #16.
These cams are mostly sold on ebay. To be sure I get the right cam, I buy directly from the producer: http://www.ebay.com/usr/eletoponline365
You can either remove the camera case (saves 3-4g of weight), or modify the case to fix the cam to the quad.
Motors and ESCs produce electric noise and voltage drops, both is nothing you want as input for a camera. To protect the camera from that, but still feed on the flight pack, I use a 5V-stepup.
|Dec 27, 2013, 07:12 AM|
wiring and plugs
28 awg wire is a reasonable size to distribute power between the various parts. The power and motor connector on the board take 1.25 JST plugs (~$5 for 10). These plug are tiny, and difficult to use as a battery connector.
The Losi Micro plugs are a good size compromise for a battery connector that is frequently (dis-)connected.
|Dec 27, 2013, 07:44 AM|
building the quad
|Dec 27, 2013, 07:45 AM|
configuring the Pocket Quad
There are two pieces of software that can/should be installed on the pocket quad board: The bootloader and the firmware.
The firmware is running the actual operation of the quad. Without firmware, it wont fly at all. The firmware can be installed via USB (if the bootloader is working), or via USBasp over the pin connectors on the board. There are two different firmware I have tested on the pocket quad: MultiWii and BradWii. BradWii has a nicer code layout and some great improvements, but I could not get the quad as solid as with MultiWii, so Im only using MultiWii now.
The latest version Multiwii 2.3 has major improvements over any earlier version. Today (end 2013) I dont see a reason to install anything else but MW 2.3.
The bootloader is required to flash the EEPROM via USB, but it is not needed for flight operation. If the bootloader is missing or corrupt, it can be (re-)flashed with an USBasp.
equipment to connect the pin connectors on the board to USB quick&easy:
flashing the bootloader:
flashing the firmware:
modifying the firmware:
there are several files you might want to modify. In the following, I highlight the most important files and code lines:
ESC endpoints can be adjusted with the following lines, those values are good:
#define MINTHROTTLE 1050 #define MAXTHROTTLE 2020
#define YAW_DIRECTION 1
#define ALLOW_ARM_DISARM_VIA_TX_YAW //#define ALLOW_ARM_DISARM_VIA_TX_ROLL
//#define SPEKTRUM 1024 #define SPEKTRUM 2048 #define SPEK_SERIAL_PORT 1
#define FAILSAFE #define FAILSAFE_DELAY 1 #define FAILSAFE_OFF_DELAY 0 #define FAILSAFE_THROTTLE (1000) #define FAILSAFE_DETECT_TRESHOLD 985
#define DIAL_TUNING_BG #define POT_G AUX2 #define POT_A AUX3
// 50 degrees max inclination // errorAngle = constrain(rc + GPS_angle[axis],-500,+500) - att.angle[axis] + conf.angleTrim[axis]; //16 bits is ok here errorAngle = constrain(rc + GPS_angle[axis],-900,+900) - att.angle[axis] + conf.angleTrim[axis]; //16 bits is ok here
configuring the firmware with MultiWiiConf GUI:
PIDs: the PID value determines how the sensor inputs are translated into control outputs. You can either set static values (disable/comment #define DIAL_TUNING_BG for static PIDs), or use AUX channels to tune your PIDs on the go. If you want to set static values, those are good to start with:
use auxiliary channels to arm and change flight modes. If you arm via stick command and only want to fly rate mode, you dont have to check any box and need only 4 channels to fly. I am using AUX1 for arming and fly angle mode only. Looks like this:
I set both Expo values to 0, and the Pitch/Roll rate to 1.00
This gives linear input over the full range, and all curve customisation can be done in the Tx.
click "write" to save any change
click "read" to make sure your values are saved
click "reset" and start over if things are getting inconsistent
you can calibrate the accelerometer by clicking on CALIB_ACC. Get the quad as level and still as possible before you do this. Acc calibration needs to be done once only. It can be triggered and fine tuned via stick commands as well.
|Dec 27, 2013, 07:48 AM|
configuring the transmitter
Companion9x is a good tool to configure and flash a 9XR. Download and install, and then either bake your own, or use this preconfigured image: FlyingEye-9XR.bin
Here is what I have done:
Configure 3 flight modes and assign the 3POS to switch between them:
Linear channel assignment on all 4 major controls:
CH01 is throttle, and gets a different curve assigned, based on flight mode.
In flight mode (Land), the throttle curve is optimized for no payload and the curve goes all the way to zero, so you can (land).
In flight mode (Fly), the throttle curve is similar to (Land), but doesnt reach all the way to zero. You can now cut the throttle and get into a fast but controlled descent, rather than a drop out of the sky.
Flight mode (Cargo) has a slightly lifted throttle curve to provide a similar throttle response for flight with payload.
Here are all three curves:
10% CH12 mixes in hover throttle compensation. For further explanation see CH11/12
-100% MAX at switch CS2 is part of the quick calibration (see custom functions for further details)
CH02 is plain 100% aileron stick assignment
CH03 has reversed elevator and also a line for quick calibration voodoo
CH04 rudder stick and quick calibration
CH05: AUX1, only activated when both front switched (ELE and AIL) are ON. Double switch action for arming = extra security.
CH06-08: 3 pots assigned to AUX2-4
CH11 get the throttle input, but only in the center. If throttle is at upper or lower end, CH is zero. This is done through the following curve:
CH12 then receives input from CH11, halves the amplitude, shifts it into the positive part of the range, and multiplies it with pot 2 input. This allows hover throttle (around stick center) to be modified without changing throttle end points. I use this to compensate for power loss throughout a discharging flight pack.
I had to do the following channel finetuning to center all sticks:
Here are the custom functions:
CS1 is an (unfinished) experiment. No specific function (yet).
CS2 is active when the Trainer switch is pulled with AIL (arm) switch is not active. This is picked up in the mixer table to simulate the gyro calibration stick combo.
CS3 is triggering when armed and in flight mode (Cargo). This is picked up by timer2 to count the shorter flight time, so it only beeps at 2:30 when flying with payload.
|Dec 27, 2013, 07:49 AM|
configuring the camera
there is a massive thread about the 808 #16, that will probably answer all questions about the camera.
I just want to point out a few settings that are useful for this particular use case:
Deactivate the time stamp. Since the cam is powered from the flight pack, the camera is frequently losing power and reset the date, so a time stamp is pretty useless.
Movie stamp=;set date / time stamp on or off,0:off,1:on
LED=;set LED flicker when recording,0:off,1:on
Movie Flip=;set movie rotate,0:off,1:on
Auto Record=;set movie auto record,0:off,1:on Power on=;set system power on time,0:delay,1:fast
Download it, rename, put on the root of the SD card, and do the following:
|Dec 27, 2013, 08:52 AM|
If you configured everything like described above, you can operate the quad like that:
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