Reducing Vibration on Your Multicopter for Aerial Photography

MK Hexacopter with PhotoshipOne Mktr Pro Camera Mount

MK Hexacopter with PhotoshipOne Mktr Pro Camera Mount

Vibration Ruins Video

Getting clean video with a multicopter can be a difficult and frustrating task.  The reason, of course, is that slightly out of balance motors and propellers cause significant amounts of vibration.   If you’re only taking stills, then you can use a high shutter speed to get a clean picture.  So with stills you can tolerate a certain amount of vibration without affecting picture quality.

However, with video you usually don’t have the option of using high shutter speeds.  And video cameras and DSLR’s that have CMOS sensors are particularly sensitive to vibration.  Even after you’ve bought the best motors and props, there’s still vibration that needs to be damped out.

Most often, it’s a trial and error process to get good, low vibration.  You add some damping between the camera mount and the helicopter, go out and shoot some video with the new damping, and then process the video to see how good it looks But it’s often hard to judge whether the change you made is heading in the right direction.  You may have lowered the vibration a little, but you can’t really tell when the video hasn’t changed much. You have no accurate reference against which to measure.  You may need to do many experiments just to see if you’re damping material is going to work out

Wouldn’t it be easier and quicker if there were a way to measure the vibration when you spin up the helicopter and “see” even a slight improvement?  That’s what vibration meters are for.  But vibration meters are expensive and heavy.   Or are they?

Measuring Vibration with Your iPhone

I’ve found two iPhone apps that turn your iPhone into a vibration meter.  These apps work extremely well. They remove much of the guesswork and trial-and-error experimentation.   One of these apps is called “Vibration” and the other is called “Seismometer.”  Here are the websites for Vibration and Seismometer.

Though they both measure vibration, these two apps are quite different. Here are some points of comparison.

1. Vibration measures vibration in all three directions: x, y, z.  It gives you 3 separate graphs, capturing the vibration in each direction.  On the other hand, Seismometer gives you a one dimensional graph that captures the RMS energy in all directions. It might seem that one dimension would be limiting.  But I found it to be quite good enough (see example below).

2. Vibration will only sample for 10 seconds.  You can delay this sample up to 100 seconds. Seismometer, on the other hand, starts sampling as soon as you hit the button, but continues until you press the button to stop.  So, it will sample indefinitely. As you can imagine, Seismometer is more convenient to use, because you can start it and then take off, without worrying that it’s going to measure vibration at the wrong moment.  With Seismometer, you can monitor the entire flight.

3. The little red dot that tells you that you are recording with Seismometer is so small that it’s difficult to see.   Vibration, on the other hand, has big countdown digits as it prepares to start a recording.  You can’t miss it.

4. Both tools let you email yourself a CSV (comma separated values) file with the recorded data.

5. Vibration lets you take a screen shot.  Whereas, Seismometer saves each data file in your phone as long as you like.  You can go back and look at them at any time.   Vibration let’s you email it anywhere you’d like.  However, Vibration only stores the current sample until you email it.  Then it’s gone from the phone.

6. You can’t name your files something meaningful with Seismometer.  Seismometer names them with the time and date.  However, with Vibration you can name the file anything you like.

7A. To use Vibration on a helicopter, you have to strap the iPhone in, set the delay and then push the “Sample” button.  I usually set a 20 second delay, which gives me time to spin up the helicopter and get it into a hover before Vibration starts its measuring.  This is a bit tricky, but you get used to it.  As far as I can tell, neither tool allows you to attach a note to a file to give it a meaningful description.

7B. To use Seismometer, you just push the start button, step back and spin up the helicopter.  It records the whole time. When you land, you just turn off the recording.  While Seismometer is easier to use than Vibration, for the most part, it does have one problem.  The little red “dot” that tells you that you are recording is extremely small and difficult to see when your iPhone is strapped into a camera mount.  This “dot” is barely the size of a period.  More than once, I thought I was recording, only to discover after landing that I hadn’t pushed the record button hard enough.

8. Vibration is $4.99 at the Apple Store.  Seismometer is $0.99.  Both are bargains at these prices.

Tuning a Multicopter with Seismometer

In order to get clean videos from my hexacopter (6 motors, 6 propellars),  I tried many different props (discuss different props and vibration).  After balancing, I was still getting a bit of vibration.  This was probably the result of imperfect balance and slightly out of balance motors. I thought that putting some rubber dampers between the helicopter and the camera mount might help.  I had just purchased Seismometer, so I decided to measure the vibration at the camera mounting plate before adding the rubber dampers.  Here’s the setup.

Here’s a picture of my iPhone strapped on to a Photoshipone MktrPro camera mount for testing.

iPhone on Mktr Pro camera mount running Seismometer app

Here’s a screen shot of the Seismometer output during a fairly tight hover.

Vibration at the camera mount without rubber dampers.

After adding four 10mm rubber damper between the camera mount and the bottom of the helicopeter, here’s the resulting vibration.  I put the helicopter into a similar hover as in the first sample.  In this configuration, the camera mount is hanging by the rubber dampers (picture).  I found a similar level of damping with 8 rubber dampers, which safely supports more weight.

Vibration after adding rubber dampers as measured by Seismometer.

As you can see, the rubber dampers lowered the vibration considerably. Seismometer displays with a log scale.  To my eye, it looks like about a 5x reduction in vibration amplitude.

Don’t Forget the Propellers

After adding the rubber dampers, I was still getting some jitters on cameras with CMOS sensors.  I had been using APC propellers.  These are inexpensive, composite props, which I balanced using a static balancing tool.   I was using 12 x 3.8 slow flyer props.  These props have considerable flex.  This can create excessive vibration under heavy load (especially when descending into the prop wash, etc.).  I switched to Xoar wooden props at roughly the same size, 12×5.  The Xoar props are much stiffer and don’t tend to flex under varying loads.  The videos were dramatically smoother.  In addition, the ESC’s were running cooler as well.

Canon G9 Will Not Power On

G9 Fails to Power Up

This is a short post about an experience I had while trying to package up a used Canon G9 for sale.  I owned this G9 for several years.  It had been very lightly used, so I wasn’t expecting a problem.

As I was checking it out I heard something lose inside.  I powered it down, shook it, and the noise stopped.  Little did I know that a screw had become lose, and lodged itself on one of the circuit boards.  When I tried to power it up again, it was completely dead.  Nothing lit up, no sounds, nothing.

I did some quick searches on the web to see whether others had the same problem with the G9 and what Canon’s response had been.  Mine was way out of warranty, so I wasn’t expecting a free repair.  To my astonishment, I found several threads with a very large number of similar failures. Canon was not acknowledging the problem, but they were fixing it for about $160 (US).

The Solution

Here’s a thread on amazon that I found especially helpful.  It gives you a sense of who will repair it and how much it will cost you should you have this problem with a G-series camera.  Canon G9 failure thread on Amazon.

Lessons and Tips

But the main reason I made this post is to remind you that if you hear something lose inside a camera, don’t power it up.  Instead, remove the battery and take it to be repaired.  The Canon G9 repair is very quick and cheap if the screw hasn’t shorted anything out.  But if it happens to land on the main CPU board and short it out, the repair is expensive.

The other point I wanted to make is that a little loctite or CA glue would have kept those screws from ever coming out.  It amazes me that Canon did not take this precaution on a G-series camera.

So, if you’re going to use a similar camera for aerial photography, you may want to consider taking it to a repairman to have the screws properly secured.   I wouldn’t expect this to be an issue for a pro-level DSLR.  However, a point and shoot, or low end DSLR may be at risk.  A little prevention may save you the loss of valuable footage.

Finally, the last lesson I learned from this experience is to search the web for user experiences before buying the camera. If I had searched on ‘Canon g9 problems’ before buying the camera, I would have made a better purchase decision.

 

 

Outfitting the Gaui 500X for FPV and Aerial Photography

Unafraid to Crash

Several months ago I picked up a Gaui 500X Quad Flyer kit.  I wanted an inexpensive platform for learning FPV (first person view) flying and light aerial photography.  I have several larger multicopters for professional photography.  But I wanted a small practice aircraft that would be cheap to fix.  I didn’t want to be afraid to crash it, while improving my piloting skills.  This article takes a look at the Gaui 500X for this purpose.

Gaui 500X First Impressions

When I first opened the box, I was impressed with the engineering quality of the whole package.  For example, the ESC’s are amazingly tiny.  They fit inside the quad’s arms, so both wires and ESC’s are hidden.   Very nice.  The wiring harness is an extremely small and simple design, constructed from bullet connectors soldered together.  Reliable.  There’s a very light weight blade guard to prevent blade strikes should the copter bump into something.  The arms of the quad are foldable, so you can pack the whole thing in a small canvas bag (included in some kits).  And there’s an optional lighting kit with LED’s for each motor mount.  This makes day flying easier and night flying possible.

Good Motors, Good Electronics

In case you’re wondering whether there might be overheating problems with internally mounted ESC’s, the motors and ESC’s run warm, but never hot.  Even with heavy loads (over 1600 grams but under the 2200 gram limit), I’ve never had overheating (unlike my larger multicopters).    The Scorpion motors are small, but efficient and ample for the quad plus a small camera.

Gaui 500X Motors and Electronics in an AGL Hobbies frame

Gaui 500X Motors and Electronics in an AGL Hobbies frame

  Continue reading

A Short Cut To Getting Your Camera In The Air

I’ve spent more than a year trying to build a helicopter that can lift a small DLSR and give clean, crisp stills and vibration-free video. I’ve built a variety of aircraft: some single rotor (with collective pitch) and several multi-rotor helicopters. I’ve also experimented with different camera mounts, and different flight control computers.

This is part 1 of a series of posts describing what I’ve found that works best and how you can build your own aerial platform (or what to buy if you want someone else to build it). This information can save you a year of trial-and-error experiments. Better, you can go straight to a solution that will work for you without wasting a lot of time or money.

First, here’s a picture of 6 rotor helicopter, a hexacopter, with a Skyrover camera mount and camera. I finished this one recently and it gives the best results for stills and videos that I’ve been able to get so far. In future posts, I plan to take you through every step of the build process. I’ll explain my choices and the reasons for them.

Hexacopter with Skyrover camera mount, MK electronics and D90

Here’s a view from the top.

Hexacopter with Skyrover camera mount and D90, top view

I’ve found that multicopter configurations with 4, 6, 8 or more rotors (propellers) to be the smoothest, most stable and easiest to fly. On these multicopters the rotor has a fixed pitch. So the only way to cause the multicopter to roll, pitch or yaw is by changing the speed of the motors relative to each other. Translating the joystick movements on a remote control into speed variations of the motors is done by an on-board computer. How stable the multicopter is in flight (especially in the wind) is determined largely by the computer and the quality of its software.

I’ve found that the computers made by www.Mikrokopter.de (sold in the US by www.Mikrokopter.us and by www.quadrocopter.us) to be particularly good and probably among the best available. I’ll discuss the reasons why I think they are a good choice below.

Another contributing factor to stability and smoothness in flight seems to be the number of rotors. Having looked carefully at dozens of videos, I’ve noticed that even with the best multicopters, there’s a little bit of jerkiness, or low amplitude, short duration roll movements. I call these micro-rolls. Usually, they appear as tiny and brief (barely noticeable) jerks rolling to the right or left. These movements are most often caused by sudden stick movements by the pilot. They are also caused by wind. They are subtle and most viewers don’t notice them. But professional videographers notice them. So if you have discriminating clients, you’ll want the smoothest copter you can get.

When comparing videos, my subjective judgement is that octocopters (8 rotors) show the least of these micro-rolls. If carefully flown, you can get very smooth movement with an octocopter sometimes with no visible micro-rolls in the video. It looks like the octocopter is on a pole, not flying through the air. Hexacopters can be reasonably clean too, but they seem to be a bit jerkier. Quadcopters are usually a bit worse. The reason octocopters are immune to these movements is that there is more mass at the ends of the arms. And the arms on octocopters tend to be longer to make room for the propellers. So it takes a lot more energy to roll or pitch an octocopter.

You might think that a properly stabilized camera mount would absorb micro-rolls. I haven’t seen one yet that removes them completely. Please let me know if you find one. The camera mounts tend to be better at removing slow, large amplitude movements. So, my recommendation is that if you’re building a multicopter for aerial photography, go with a 6 or preferably an 8 rotor design.

An actively stabilized camera mount can keep your camera pointed where you want it, even when the multicopter is pitching and rolling in the wind. The camera mount should also absorb vibrations caused by the motors and rotors. The Skyrover camera mount (available at MikroKopter.us) is an inexpensive mount with active stabilization for pitch and roll. It is designed to work with the Mikrokopter computer and software.

The Skyrover doesn’t have gyros or accelerometers itself for stabilization. It comes only with servos. It relies on the Mikrokopter computer (or similar) to provide the right signals to the servos. While this is a good arrangement and works reasonably well, it is possible to improve it. The main reason it’s not perfect is that the gyros, which sense motion, are on the Mikrokopter computer board. So they’re not actually sensing the camera’s motion directly. The camera is not rigidly attached to the multicopter’s frame. There are soft rubber shock absorbers connecting the camera mount to the copter. So a better arrangement would be to have the gyros mounted on the camera mount, so they are sensing the camera’s movement directly. You can set up the Skyrover to work like this (there’s a gyro+computer product called PicLoc you can use for this), but you need to provide the extra gyros and hook them up yourself. Not difficult, but you need to decide whether the effort is worth the slight improvement.

But even with the standard arrangement of the Skyrover and Mikrokopter, the Skyrover is amazing at absorbing vibrations and stabilizing the camera. I’ve shot stills at dusk at 1/125 second and got results that were consistently tack sharp. Can’t do better even on a tripod.

For video, the results are also quite good. The Skyrover mount compensates for helicopter movement quickly, smoothly (important for video) and with lots of torque for heavier cameras. The current version of the mount will accomodate a camera body that is 5.75 inches wide. This is wide enough for most small and medium size DSLR’s. Though it’s not quite wide enough for a Canon 5DII. My understanding is that a wider carriage version of the mount will be available to handle larger cameras (Spring 2011 time frame).

Equally important, the Skyrover is mostly made of aluminum. It can withstand hard landings and outright crashes, often protecting the camera from damage. At 600 grams, you can lift it easily with an octocopter or hexacopter suitably powered (we’ll explain what this means later as well). I prefer aluminum to carbon fiber. Carbon fiber can shatter in a crash. Aluminum bends. So, you can bend the aluminum back and (hopefully) keep flying.

To be continued…

How To Get Started In Aerial Photography


What’s It Really Take?

Back in November 2009, I posted an article about choosing (radio controlled) helicopters for aerial photography. At the time, I was looking for the cheapest way to get professional quality results for both still and video. Back then,  you’d need about $3k worth of helicopter (or more). You’d also need to hire a pilot, or spend a year or more likely two years learning to fly it yourself.

Well, all that’s changed. There are new helicopter designs with ever more sophisticated electronics. The new designs are cheaper, more stable, easier to fly, stay in the air longer, and are safer and easier to repair than “conventional” helicopters. And as digital cameras get smaller and lighter, the loads placed on these helicopters are reduced. This makes it possible to use smaller, less powerful helicopters to get the job done. Sound good? Here are the details… Continue reading

Start Your Own Space Program for $148

The Vision

This is a story that I find inspiring.  Since it’s also about photography and space, I find it even more inspiring. It’s about two MIT students who wanted to photograph the “edge of space.”

It started when Oliver Yeh had a vision. He wanted to see the curvature of the earth and the blackness of space from high up in the stratosphere.  Many of his friends thought he was crazy.  Not Justin Lee. Lee accepted the vision and made it his own.  So together they set out to accomplish the task.

The Ingenuity

Like others before them, Yeh and Lee decided to use a weather balloon  filled with helium  to lift a small camera up into the stratosphere.  They bought a 300 gram latex balloon online.  Balloons are capable of reaching altitudes of 20 miles or more. Unlike others before them, Continue reading

A Fast and Easy Way to Find the Right Tool in Photoshop

Too Many Tools, Too Few Buttons

With each release of Photoshop, new tools and filters are added, as you would expect from a product that is continually being refined and improved.   Sometimes the consequences of this growth are changes to the user interface that actually make Photoshop a little harder to use for those of us who were used to the previous version.

For example, in CS3 the tool palette has 24 buttons for 59 tools.  That’s a lot of tools that aren’t in plain view.  So if you are a casual user of Photoshop or you’ve just upgraded to a new version, you’ve got some hunting to do.

Exploded View of All Tools

To make it easier to find the tool you want, we’ve created a summary sheet Continue reading

Importing Long Videos With Final Cut Express

Problems with MP4 Importing

In a previous post, I discussed difficulties I encountered while exporting MP4 files with Final Cut Express 4.0.  In this post, I will discuss difficulties I encountered while importing MP4 files with Final Cut Express. In particular, I noticed that FCE sometimes truncates mp4 clips during import.  I found that I could import 20 megabyte mp4 clips just fine.  But clips just over 30 megabytes in length were shortened.  They were truncated so that they terminated early.  I couldn’t find a setting in the user or system preferences that would allow me to import longer mp4 clips without truncation.

MPEG Streamclip to the Rescue

The solution I found is to split long mp4 clips into shorter clips, each of which can be imported into FCE successfully.  You can put the clips back together once they are inside FCE by dropping them into the same sequence.  The tool I used to split a clip is a very nice freeware conversion and editing utiliy called “MPEG Streamclip.”  You can download MPEG Streamclip at www.squared5.com.  It is available for either Macs or PCs.

Click by Click Solution Continue reading

Exporting Videos With Final Cut Express

New to Final Cut Express

I’ve been teaching Photoshop to photography students for about 12 years.  When a recent student asked for training videos to supplement the instruction, I decided it was time to make some.  Not knowing what I was getting myself into, I went out and got a copy of Final Cut Express 4.0.  And so the fun begins.

Final Cut Blurries

After reading a few sections of the manual that comes with FCE, I was able to assemble a few mp4 video clips into a sequence.  However, when I tried to export the sequence to get a final video result (also an mp4), I hit a roadblock.  The resulting video was quite blurry and in a dynamic way.   That is, text in the video would sometimes be crisp and sometimes become a blur.  It was as if someone was pouring water over freshly painted watercolor. The blurriness would flow around the image.   I assumed that this was some kind of compression artifact, so I tried using different parameter settings during the export to fix the problem. No luck.  I finally concluded that there must be a bug in FCE’s processing of mp4 files.  So, I tried a different output format.  When I chose the Quicktime Movie format (an mov file), things started to work much better.  With the right settings, I was able to get clean, crisp output.  In this post, I’ll take you through the settings that I found to work, so you can get high quality exports without a fuss.

Click-by-click Solution Continue reading

Take Your Camera Out In The Snow!

Bad Weather, Good Photos

It’s snowing here today.  Such stormy weather can provide opportunities for beautiful and unusual shots. So, I was very eager to get out and see what I could find.  However, there’s nothing worse for your camera than getting either water or sand inside it.   So as I was getting ready to go out and take some pictures,  I looked around the kitchen for something to protect the camera.  Unfortunately, I discovered that I was out of zip-loc bags.

Zip-loc Raincoat

A large zip-loc bag can make an acceptable raincoat for a DSLR or similar camera.   The camera goes inside the bag, and the lens pokes out the opening of the bag.  You can snug the bag around the lens barrel with a rubber band, or sometimes the zip-loc itself will hold.  But what do you do if there are none around? Continue reading