Pendulum Rig Kit Documentation
This is first stab at manual for the forthcoming Pendulum Rig Kit.
pendulum kit documentation
The Public Lab DIY Pendulum Rig Kit gives you a colletion of basic materials with which you can create a variety of camera rigs, allowing you to build safe and stable camera platforms for your aerial mapping projects.
These instructions will give you step-by-step instructions for the basic setup and configuration of your kit, including a few example riggings. But this kit is meant to be hacked, so we encourage you to create new and custom rigs, and to share and participate in our online community, collaborating with other Public Lab contributors to create new and better methods.
For more information, check out publiclab.org/pendulum-kit. There we will maintain this documentation, and update it as the community improves the design and usage. For the bleeding edge, visit publiclab.org, and look for research notes tagged with "pendulum rig" and "aerial mapping." There you will see the latest advancements and ideas from the community, and you can create your own documentation to show what you've came up with.
A note on cameras:
This kit is designed to work with small, point-and-shoot cameras, such as the Canon PowerShot models, and the Mobius ActionCam keychain cameras.
The PowerShot cameras provide a high-quality image, but are heavier. They can be found cheaply at thrift-stores, and older cameras still provide a very usable image quality for mapping applications.
Mobius cameras are very lightweight and provide high-quality images. Since they are CCD sensors, they do introduce some "rolling shutter" issues, and the lens that ships with the camera is a very wide angle, which introduces a fish-eye effect that can make stitching (combining) images difficult.
Both cameras allow users to set them up to take images at regular intervals, which is critical to get usable mapping images.
This kit is not intended to carry larger cameras, such as DSLRs or anything larger than the cameras described above.
- 4 9" wooden dowels
- 1 8" section of flexible PVC tubing
- 4 thumb tacks
- 10 rubber bands
- 4 zip ties
- 1 8" length of 16 guage galvanized steel wire
- 2 paperclips
- 1 #3 rubber stopper with hole
- 1 12" length of nylon threaded rod
- 1 mini-ball tripod head mount
- 1 set instructions
What you'll provide:
- soda bottle
- craft knife
- drill bit
- kite, balloon or pole
The basic rig:
Cut a piece of flexible tubing to 2" in length. Press the ends of two dowels into this 2" tubing, until the meet at halfway point.
Position a thumbtack about 1/2" from the end, and press until it just enters the dowel. If you press it all the way, it will become harder to remove, and it may split the dowel. It just needs to bite into the wood a bit in order to provide a postive lock.
Repeat this process with the other end, locking the other dowel in place.
Test the joint by pulling on both dowels and ensuring the ends stay seated in the tubing, even with a reasonable amount of force.
With the remaining tubing, use a thumbtack to start a pilot hole, about 1/2" from one end.
Use a craft knife or very small drill bit to bore out a hole just smaller than the craft wire. (We use Xgauge wire, so a 1/16" drill bit is about right. You can also use a craft knife or awl to make the hole).
Repeat this on the other side of the tubing, so the craft wire can pass through the tubing as shown.
Once the wire is in place, use pliers to bend the ends of the wire back to form small U-shaped returns, about the same shape as on a paperclip. This craft wire will be how you suspend the rig from your kite or balloon line.
This is the basic rig. From here, you can attach a camera, and then connect the completed rig to a flying line or pole.
ProTip: Use a marker to make it easier to find the same tack-hole in the tubing and dowel each time.
Attaching a Mobius ActionCam to the dowel.
Method 1: rubber bands
Provided you are using quality rubber bands, which are inspected to make certain they are in good condition and free from knicks or wear, you can get a solid connection between camera and dowel by simply rubber banding it in place.
Make sure you do so using multiple bands, providing additional strength and redundancy.
Make sure you do not obscure the buttons or LEDs on the camera.
Make sure you carefully test the connection to ensure it is securely fastened prior to flight.
Method 2: zip ties
Another method is to use plastic zip ties. This method will use three, removable ties to secure the camera in place.
The first tie will provide the "stopper" at the base of the dowel. Attach the zip tie to teh base of teh dowel, and pull it tight, as tight as you can with you fingers.
Then slip the zip tie off the base, and continue to tighten the tie one, additional "click." Then press the tie back onto the base of the dowel. It should be difficult to do this, and you should need to use a flat surface to fully slide this back on. If it can be removed easily, tighten an addional "click" and replace until it is firmly fixed.
Ensure the tie wraps around in a clockwise manner, or forms a "6" or "9" shape, as shown:
This will allow the camera to properly seat in the following step.
Combine two zip ties as shown. Repeat this step, so you have two pairs.
Rest the camera agains the dowel as shown, with the buttons facing away from the dowel. Use two zip ties to cinch the camera down. Make sure they go in opposite directions, as this will provide "legs" that allow for additional protection.
Once the camera is secured to the dowel, tuck the tail of the "stopper" zip tie under the other ties, and turn the dowel to unsure the camera is securely seated as shown.
The final product:
Method 3: hybrid
you can use the stopper zip tie method, and tuck it into rubber bands.
Method 4: kite string and paperclip method
find details in research note, here
Method 5: clothespin method
this method was born out of this research note, but gives a basic method for securing the camera to the dowel drop.
First, hold the clothespin firmly open, and press the ends into the opening of a small piece of 3/8" flexible PVC tubing. They should barely fit, and once inside, should provide a strong connection. A thumbtack should be pressed in through the tubing, biting slightly into the wooden clothespin on one side. the other side of this tubing can be similarly secured to the rig's bottom dowel.
the resulting connection is stronger than you'd imagine!
Protecting the camera:
The soda bottle rig
This is the method for the risk-averse. It adds weight, but better protects your camera from impact or landing in damp terrain.
Using scissors, cut a 2-liter soda bottle rougly in half, leaving about Xinches of bottle below the bottle neck.
Remove the bottom length of dowel.
Position the rubber stopper on the dowel, about X" above the Mobius camera. Make sure the stopper is placed with narrow end facing up, so that it will prevent the bottle from falling off the rig.
Slide the bottle down over the stopper. Ensure the stopper is in the right position, allowing a few inches of the bottle to protrude below the camera. You may want to take a test photo to ensure the bottle is just out of the camera's range of view.
Pull the bottle down snug onto the stopper. Then replace the dowel into the rig and replace the thumbtack, using the same hole as you made before, when first building the rig.
*NOTE: The rubber stopper is quite grippy. If you pull too hard, it may be quite difficult to remove. If this happens, you may need to remove the dowel first, then press the stopper out.
The soda bottle "visor"
This is a lighter weight method, which offers a lesser amount of protection against impact and abrasion, but weighs far less.
Simply cut a rectangle of plastic from a soda bottle, then use this to provide a "visor" or protective material, jutting out in front of the camera lens. You can attach this visor to the camera using zip ties or rubber bands, or even slide the visor inside of the existing rigging.
When using the visor with zip tie method, you can use single ties, making feet that project downward as shown.
Image of visor rig with two zip tie "feet"
Attaching a point-and-shoot camera
For point-and-shoot cameras, we recommend using a basic "soda bottle rig." This method involves hanging an empty 2-liter soda bottle from the rubber stopper, which attaches to the base of the dowel. The camera is suspended inside this bottle using rubber bands.
As all point-and-shoot models are slightly different, the following is a general overview of the method. You will want to use common sense and caution in adapting these guidelines to ensure you are safely and securely attaching your camera to the rig.
As a failsafe, we recommend using your camera's lanyard connection to provide a positive connection in case any element of the rig fails. You can attach a piece of kite string or other stron line directly to your camera, then pass this string up through the bottle neck, and attach it using a carabiner or by tying it directly to the main line.
Attaching the rig to a kite or balloon line:
Once your balloon or kite is aloft, about 50' down the line you will tie in your pendulum rig.
The tubing will maintain a natural curve. Make sure you use this curve to let the rig hang at a natural angle.
Image: this side to ground <- / -> this side to skies
Wrap the flying line four or five times around the wire on each end of the rig. Make sure the spiral is continuous, going in the same direction throughout, as shown: Correct Incorrect
Attaching the rig on the Public Lab Pole Mapping Kit:
(probably include these instructions with the pole kit) Instead of hanging the rig from a line, you will be fitting the end of the flexible tubing over a threaded rod.