The Flying Flowerpot has gone to the great beyond, aka the garbage bin. It was a great first drone to build, I learned a lot, but it had its share of problems.
For the last flight, I programmed it via Mission Planner to fly a rough polyhedron at 60 feet over the River Mills Park near the Potomac River. It accomplished this and then loitered. When I switched it back to Stabilize mode, it somehow became unstable and did a death dive. This broke the internal frame, two arms, two propellers, one motor, the battery mount, and the flower pot. The basic electronics are fine, but I will have to get a new frame kit and motor at least. The video is below.
The new build will take some time, so postings may be sporadic. Have a Merry Christmas and a Happy New Year and Happy Hannukah.
I finished the Flying Flowerpot quadcopter rebuild and had a successful basement test flight in the new configuration. Changes since the last blog posting:
Moved the camera mount again, to the upper level but with a new mounting bracket so the camera is out front between the props.
Moved the receiver slightly.
Tidied up the wires.
The following photos show the Flying Flowerpot 2.0:
Top view, no flower pot
Note the receiver attached to top level with double sided foam tape
Partially Rebuilt Flying Flower Pot (Pot removed for clarity)
One of the advantages of building your own quadcopter is that you know how to fix it if it breaks, and you can make improvements at the same time. It is kind of like the Six Million Dollar Man TV series: "We can rebuild him. We have the technology. We can make him better than he was. Better, stronger, faster." The Flowering Flowerpot, after its last flight and crash (see previous blog post), needs this treatment.
First, I got rid of the battery monitoring module, which might be causing problems and I cannot figure out how to use it.
Second, I rewired the control module (APM) to receiver wiring to get rid of the servo extension cables and labeling.
Rewiring, receiver is on the left
Third, I repaired the damage to the quadcopter - a broken arm and a broken motor mount on the end of another arm using 5 minute epoxy, which smells like crap and gets everywhere.
Broken motor mount
Break in arm
Fourth, I got rid of the structure holding the GPS and compass and mounted them using nylon standoffs on the third level.
GPS remounted
Fifth, I removed the long landing gear and mounted the camera on top. The long landing gear seem to cause a lot of damage in crashes.
camera mount
I also ordered a bunch of spare parts (arms, motor mounts, landing gear..). Stay tuned for more updates as we get the Pot ready for its next adventure.
Had a crash yesterday with some damage. Nothing serious and I was able to repair it quickly. The "Flying Flower Pot" seems quite robust. The problem was a propeller that came loose, causing the quadcopter to fall from about 20 feet to the pavement. I then checked all the bolts and screws and found a few that were getting loose due to the vibration, so check your quad before every flying session.
I am still coming up to speed on usng LiPo batteries in models. The latest thing I learned is that you should not store the batteries fully charged, or let them fully discharge. The prevailing wisdom is that you should store them at 3.85 volts per cell, or 11.55 volts for the 3 cell packs that I am using.
I don't have a fancy charger yet so I was not sure how to get them down to 11.55 volts. Luckily I remembered enough of my old Circuits class and am enough of a pack rat that I could create my own discharge circuit.
Using an old 50 watt 7.5 ohm resistor, a homemade heatsink for the resistor, some wire, and my newly purchased XT60 connectors, I was able to solder together a discharge circuit.
I monitor the voltage with a voltmeter and was able to discharge my packs to 11.55 volts and then store them in a LiPo protective bag (good precaution) on the concrete floor in the basement away from combustible material. Always stay close to and monitor your batteries continuously when charging or discharging them.
Note that LiPo batteries can be dangerous and you should follow ALL manufacturers' warnings on the use, storage, and charging of these batteries. I am not an expert and you should check the Internet and the manufacturer of your batteries and charger for accurate information.
This mid size low cost intermediate grade quadcopter is easy to fly and includes a camera. It is a good trainer before moving on to more complicated and expensive machines. The unit is fully assembled and you just have to charge the flight batteries, insert transmitter batteries, and then you are ready to go.
The UDI 818A is available from Amazon and others for about $65 to $85 US. This includes the copter with camera, transmitter (mode 2), extra battery, USB charger, and extra props. It comes in white (my unit) or black, they are identical except for the color. All you need to add are AA batteries for the transmitter.
Design
The unit incorporates a horizontal plastic prop guard assembly to help preserve the copter when you bump into something. You can hit an obstruction without damaging the quadcopter. You can turn the camera on and off with the transmitter and it takes decent video (see the youtube link below). Other than that, it is a pretty standard 4 channel quadcopter with 6 axis gyro stabilization.
Documentation is terrible - a google translation from Chinese with some made-up words thrown in. Read it to get some basic ideas and a good laugh.
Flying
Relatively easy to fly, the throttle is not too sensitive and the controls work well. Flight time is about 7 mins on one battery and it takes about 1 to 2 hours to recharge. The inevitable crashes do not seem to mar walls or ceilings, in case your wife or mother is wondering.
This can be flown outdoors if it is fairly calm, but be careful as it will be harder to control than in controlled indoor environment.
Accessories
There are no accessories and you cannot add any due to the small size of the unit. You may want to buy extra batteries or props that can be found on Amazon or Ebay.
I learned a few things at the Meetup that I will pass along.
Flying with larger propellers will make your video smoother but make the quadcopter less maneuverable. I have 10 inch props on my homebuilt but I could go to 12 inches.
You cannot assign a separate channel to the AUTO function on your APM which triggers an autonomous mission. AUTO is just a flight mode so it must be controlled by the same channel that allows you to use Stabilize or Loiter. That was one of my questions that I got answered.
There is a capability called "OpenTX" that allows you to program inexpensive radios to do almost anything. The radio is the 9X which is available branded Turnigy, Flysky, etc. and costs $50 or so. You can also add a board inside the transmitter to allow USB hookup, it is from Smartieparts and cost about $20.
You can get plans to print a quadcopter frame using a 3D printer.
I went to a "Meetup" of the DC Area Drone User Group yesterday. It is essentially an informal meeting of like-minded individuals organized through the Meetup application.
The meeting was very useful as we had a great mix of beginners like me, experienced folks, large drones, small drones, different radio setups, etc. I was able to ask questions of some of the experienced folks about how to set up my controller and radio, what props to use, where to buy parts, etc. There was also an opportunity to see what other people had done with their drones - construction techniques, equipment, and so on. You also get to meet people and exchange contact information.
If your community has a similar club or users group, I encourage you to attend as it is a great way to meet folks, get questions answered, and learn.
I am starting to play with the Mission Planner software which allows you to program your drone-quadcopter, read logs, and program autonomous "missions". One of the interesting aspects is the ability to download logs from the flight controller and plot your flight paths on google earth. Mission planner outputs a KMZ file which can be read by Google Earth and viewed in the application. The roller-coaster-like plot in red above shows my flight of November 29th over my house. The video from the onboard camera was posted in a previous blog entry. You can see the takeoff from the driveway, flight over the house, then back climbing, then doubling back, followed by a collision with the roof and a crash landing in the bushes.
Yesterday I had some successful flights (see video above) but one crash landing that required some repairs - nothing major - a couple of new propellers and reattaching the GPS mount with glue.
Today I had some great flights in a park by the river with fabulous panoramic views under clear blue skies with little wind, but the camera stopped working so there is no footage. I also tried the althold and loiter functions and they worked like a charm.
I am getting about 10 minutes of flying time with a 2200mah battery pack and I have ordered a 3000mah pack as a spare. They take a while to recharge (a few hours).
Recently, the FAA (USA aviation regulator) drafted some new rules on drones, which are unfortunately not very good. The proposed rules say that anyone who commercially flies a drone needs to have a pilot's license. Commercial drones today are mostly used by photographers for wedding pictures, real estate ads and by film makers. In future, they might be used for crop surveying, search and rescue, and police work.
The FAA does need some rules to ensure that people don't fly drones near planes, over crowds of people, or near secure areas. But what is the point of requiring a pilots license?
On the one hand, pilots know the rules of airspace use, and might be more cautious and careful.
On the other hand:
There is no evidence that flying a full size plane makes you a good drone pilot. In a plane, you fly a large vehicle using a stick, pedals, and gauges and land and takeoff from a well-managed airport. A drone is flow from the ground almost anywhere using a little box with joysticks.
It is expensive to get a pilot's license, and I am sure that wedding photographers have better uses for their cash and will likely not get a license.
It would be a lot smarter to have rules for commercial drones like this:
you have to pass a test showing you can fly a drone (simulators are available for the FAA to test this)
you know the rules through a written test
the FAA checks your background - no criminals, no terrorists, etc.
your drone is registered and carries a unique tag so it can be identified as being registered
you carry your FAA license with you when operating your drone
some basic rules should be written for hobbyists and commercial operators saying no drones over crowds, no drones over 200 feet within 2 miles of an airport, no drones in airspace designated as secure like over the White House, etc.
I managed to get some quadcopter test flights done with my Veho VCC-005 action camera attached, both indoors and outdoors. You can see the results in the attached Youtube video. I also checked out the Loiter and Althold modes by triggering them from the transmitter while in flight and they seemed to work well.
The other day I reflected on why building and flying a quadcopter is an interesting hobby for me. It is pretty straightforward, to my mind. Two of my other hobbies that I started when I was young were personal computers and model building. Drones combine these two together since you build the drone and program and interface it with a computer. There is also a bit of photography thrown in, which is another hobby of mine. I have other hobbies that are not conducive to drones like wine-drinking so we will not add those to the mix.
I learned a few things from building my first quadcopter drone.
The USB port is very fragile, attach a permanent short extender cable to connect to your PC. Otherwise, you will be buying a new controller.
You need to take time to think as you assemble the drone. There are lots of ways of attaching components and taking some time to think will yield a better result. Spending time with the Mission Controller application will help you set up your drone, understand how it will work, and allow you to test some of the functions before flying.
The best places to get pieces are online stores like Amazon and Hobbyking, Home Depot, and your local hobby shop.
Nylon cable ties are a great way to attach things to the quadcopter frame. Why use bolts when a simple tie will do?
Learn how the controller works before flying. There are some modes like "althold" that sound useful but should only be triggered after flying.
Make a tethered test setup to test fly your quad.
Use the Wiki, google, youtube, and manufacturers sites to find solutions to problems or helpful tutorials.
Time to see if the quadcopter really flies. You can see the successful test flight in the basement above, but the lighting is not great and Youtube has further degraded the quality to potato-camera level. The quad flies well but is a bit sensitive to throttle and needed some work on securing the battery. The not so smooth flying technique is the pilot's fault as I was trying to keep it away from the ceiling. The hovering is pretty good and the next step will be some test flights outside when there is no wind.
Well I went back and tried to fix the problems in the last test flight, which were:
ESC's not properly calibrated - I was able to get them to calibrate once, but there is something weird about how these speed controls interface with the controller.
Poor throttle control - It turns out that you should land and take off in "stabilize mode" and I was in "Althold" mode. It took a lot of google searching to stumble across this.
The receiver refused to work for a while and I don't know why. After plugging and unplugging wires, disassembling the receiver, testing and testing, it started to work again for some unknown reason.
After fixing these issues, I tried the quadcopter with no props and it seemed better. I then lengthened the tethers and ran another test flight shown above, which seems much better.
Making progress, I found the link to set up the motors, speed controls, etc and got the wiring for the ESCs and motors set up properly. Then I mounted the propellers and spent a while trying to figure out how to arm the drone, which I found at this link on the wiki.
I also needed a way to test-fly the drone, given my propensity to crash quadcopters. I came up with a system using an old piece of plywood, with holes to allow rope to be attached to the drone landing gear. The rope is wrapped around some tall screws on the plywood to allow adjustment. This is shown in the photo above and actually worked out well.
Then our first test flight shown above. The drone worked, although the controls need adjustments, particularly the throttle. You can see me testing throttles, forward motion, yaws left and right, and left and right movement - all the basic movements. So now it is back to the wiki and Mission Planner to find out how to tune the controls.
Further Progress. I reloaded Mission Planner onto my laptop and it seems to work with the controller now. The rats' nest of wiring is somewhat tamed and the receiver and controller are mounted using double sided foam tape (get it at Home Depot where they call it "mounting tape"). The extended landing gear are installed and I found an appropriate non-metallic shell to cover the electronics. Yes, it is a 6 inch flower pot, and it is perfect for the job.
The build continues. I temporarily wired up the controller, receiver, speed controls, GPS and connected to Mission Planner using my desktop PC. It is not easy to figure out exactly how to wire it as the new controller had no documentation! I found some useful information on the Ardupilot Wiki and found a basic pinout here. Hooked it up by USB and it seemed to work, but...I had the controls all wrong. After playing around with the radio calibration screens, I got the rudder, throttle, ailerons, elevator mapped correctly to the controller. I could then calibrate the compass, accelerometers, radio, etc.
The I had a brilliant idea (uh-oh). Since I would be programming things in the field, I should use my laptop with Mission Planner to set up the drone. Well, for some reason the laptop did not like to calibrate the compasses so after a few hours of frustration, it was back to the desktop where everything worked. There was also the issue of the compass being off by 90 degrees due to no markings on how to mount it, but this was easily fixed. The compass is mounted with the GPS on the wooden tower in the photos above.
Next steps are to tidy up the wiring and mounting, calibrate speed controls, attach props, and do some testing with the unit tethered to make sure it is set up properly. Stay tuned.
Back to the drawing board. I am still trying to repair the broken USB connector on the flight controller but the parts are taking forever to arrive.
In the meantime, I ordered a new flight controller from Amazon which cost $30 less, is a little bigger, and comes with a case. This required a new mounting setup which is shown in photos 1 and 2.
Stuff goes wrong when you are building a model, at least it does for me. Today, I connected up the receiver, controller, speed controls and interfaced to Mission Planner on my PC. Mission Planner allows you to set up your quadcopter, calibrate sensors, and make flight plans. My goal was just to do the set up and see how calibration works.
Two problems:
The speed controls did not seem to inteface to the flight controller - they delivered no power. Need to check this out.
As I was calibrating the compass with the USB cable installed, the connector broke off the controller card (see photos above). It looks like this is a common problem - the connector is definitely flimsy. The calibration processs has you waving the quadcopter around with the cable attached and it put too much strain on the surface mount solder joints on the board and pop. My attempts at repair using the original connector were unsuccessful.
Now I have to wait for a new connector and see if I can repair it, which does not look easy given the tiny dimensions of the connector. I also ordered a backup controller in case I cannot repair the old one. Lots of swearing and frustration and it will probably be at least a week before I am back up and running.
Continuing with the build, I attached bullet connectors to the Turnigy 25A Plush speed controls (ESC) using the soldering technique mentioned in the previous blog entry. The motor leads were shortened to 2 cm to make the wiring tidy and to reduce latency. I then used heat shrink to insulate the bullet connectors. The Turnigy Multistar 2216 motors were also mounted on the frame. The speed controls are connected to the motors under the frame arms and the connections to the power distribution panel are also underneath. This is shown in Photo 1 and 2 above.
The electronics need to be mounted on the quadcopter and there is no easy way to do it. Therefore, I combined some old model skills with some new model skills to come up with the mounting arrangement shown in photos 1 and 2.
I used a scrap piece of 1/8" aircraft plywood to make a mounting base, used some wood dowels to make standoffs, and mounted the controller and GPS unit. The GPS/Compass is mounted away from the controller to limit interference.
Continuing the build. I mounted the power distribution panel on the bottom level as shown in photo 1. It is a Hobbyking part that connects the battery up to the 4 speed controls. The only problem is that you cannot use the current sensor that came with the controller package, but that is OK for now.
Photo 1 Power distribution
I also found a reasonable guide to the software to run the controller at this location. Without this info, I was not able to find much useful info on how to load and set up the software on the flight conroller.
Photo 2 frame assembled
The frame is pretty much assembled as shown in Photo 2 and I have moved on to setting up some of the electronics wiring. The video below was quite useful in helping learn the right technique for the Deans bullet connectors used in the power wiring.
Making progress on the build. I have assembled the basics of the SK450 frame (see the first 3 photos) and you can see that it has 3 levels for mounting electronics, sensors, battery, camera, and radio. I am currently "dry-fitting" components to see what should go where. Instructions are few and far between, usually a few pages written in Chinglish. For Example: the Wiring document is called "HK Mini APM Wiring Helps". The current plan is:
Top level: sensors, controller
Second level: receiver, maybe controller
Third level: power distribution
Hanging from bottom: battery, camera
Mounted on each arm: speed control
I also received the receiver, controller and sensor kit from Hobbyking, which is very small, see photo 4. The AAA battery is just so you can judge the size. The controller came from Hong Kong but only took about 8 days to arrive with no duty payable (gotta love the USA).
