Foldable extended legs

[MonsieurAnon]

Another project that I've been working on at the same time as the Universal Camera mount is a naturally complementing upgrade for the Phantom 2; foldable leg extensions. I've found a backpack for myself that fits the Phantom 2 perfectly, but the height of the stock legs isn't enough for my experiments, so I had to think laterally about producing legs that were both longer, and more compact in my backpack.

After a few failed prototypes, including none that I have installed, I managed to arrive at a very simple design, that allows the stock compass to be fitted, for the feet to adjust to the surface of the ground they land on and for the hips to be stiff and simple.

Click on the below to see renders of the full setup





These should be on Shapeways within a few days, but I've still got some strength tests to do. I've been dropping the prototypes from ~1.5 meters with a 1.25kg weight and the last, less robust version lost 3 legs. My hope is that the one that is currently printing will survive the fall ... and it should be noted that the PLA I am using in test prints is significantly more brittle than the Nylon plastic that Shapeways sells!

Let me know if you have any thoughts or feature requests for this product.

 

[OI Photography]

Cool! I've always wanted to turn my Phantom in to an AT-AT

My only concern when looking at the current design is the lateral strength, which will be a big factor in any landing that isn't perfectly vertical...i.e. any that still have some sideways motion when contact is made with the ground.

Still I'm anxious to see these in action and I have a feeling I'll be ordering some myself once they're on shapeways

 

[MonsieurAnon]

My only concern when looking at the current design is the lateral strength, which will be a big factor in any landing that isn't perfectly vertical...i.e. any that still have some sideways motion when contact is made with the ground.

The previous failures in my tests have occurred along the length of the leg and this might have something to do with this ... that a landing initially puts its weight entirely on 1 leg. I'm a little bit curious if I can figure out a way to do suspension, but another idea that I have is to have removable skids between each left/right pair.

 

[Jimbob HiVu]

Hi,

I'm new on here, only joined yesterday. I am an engineer and have had Phantoms since February and have been giving the landing gear/rotor guards a lot of thought. You obviously have the 3D printing kit to produce stuff so I will suggest my ideas.

My ideas started with the rotor guards before the 3 axis gimbals came along. I swear by them even though I am now more experienced. Problem is every design I have seen mount in the same way using 2 motor mounting bolts. They are very slow to take on and off and with them on the quadcopter doesn't fit in a case to travel.

So to my first idea - make rotor guards with a clip on attachment instead, a curved lip to go over the outer most edge of the motor arm with a U clip that when you push up from underneath clips around the arm at its narrowest point, just inboard of the motor.


The 3 axis gimbals have arrived and now the standard legs are too short and too narrow. Tons of widened and taller copies on eBay, but all using the original mounting position.

Why not mount the legs directly under the motors?

Will give a lot wider stance and stability

Then I thought combine my 2 ideas above and the legs could be part of the clip on rotor guards.

I do realise that the front legs can't go straight down as they would be in camera view.

Just my ideas

Regards
Jim

 

[MonsieurAnon]

Jimbob; I have clip on rotor guards already. They're pretty neat.

It would be possible to have the legs come from them, but you'd have the problem of dealing with the antennas, which are designed to clip onto the stock Phantom legs. That's why you can see the same shape on mine; to accommodate for them.

Then, with high field of view lenses and cameras, you'd see the front 2 legs in most shots, because they're further forward. Many camera combinations can already see the bottom of the motors if not tilted at a downward angle and this would get harder to avoid if there was protrusions going down from that point.

What I have thought about is clip on legs at the rear of the LEDs. This would make my landing gear mechanically simpler, while keeping them more simple. The front pair could be angled outward, rather than forward, and the back pair, back, instead of outward, to create a broad landing platform, that is invisible to the camera. Unfortunately this will take me a lot of work, with careful measuring.

 

[Jimbob HiVu]

Hi again,

Can you post a photo of your clip on rotor guards please.

Did you make them yourself or buy them. If so where did you buy them from please?

Re the issue of cameras field of view seeing the front arms and motors I had had another idea to lower the whole camera and gimbal assembly below the main body. I was thinking of inserting another layer of damping balls by making 2 flat plates with a small spacer between, just enough to clear the top of the damping balls that stick through the plate allowing for one damping ball directly above a second layer (approx 14-15mm drop) This would reduce the top field of view issue showing the front arms at the top of shot and hopefully help the damping too.

 

[MonsieurAnon]

I'm trying to focus on the legs at the moment. I'll get around to posting the prop guards soon enough, but they won't be cheap on Shapeways, due to the amount of material needed.

I've done quite a lot of experimenting with dampening, and adding more layers of dampeners is not a good solution. Lowering cameras also tends to induce a pendulum effect when the auto-pilot tries to counteract the low centre of gravity. You're better off just not putting stuff in the camera's field of view. You do have some wiggle room to move it forward, but that's far too limited and neither your solution, nor moving it forward will account for having objects within the crucial from 90 degrees when the camera can see up to 140 degrees.

 

[CarlJ]

I'll get around to posting the prop guards soon enough, but they won't be cheap on Shapeways, due to the amount of material needed.

What a jip! I was already to see those bad boys too...

 

[MonsieurAnon]

You guys have spurred me into preparing them for presentation. Should take no more than a few days.

 

[OI Photography]

removable skids between each left/right pair.

I was thinking something along these lines might be necessary, or at least a brace between the legs somewhere further up their length (but still on just the left/right pairs as you said).

I'm also thinking about optimal shape or form for the feet on the end. I'll share what I come up with once I flesh it out some more in my head, but my initial thought is that a non-symmetrical design may be necessary to insure that they'll all work as needed regardless of the angle of descent when it first touches the ground.

 

[MonsieurAnon]

Cool, I'd love to see your ideas for feet. Mine were originally designed for my gorilla pod knock off that I printed for a friend.

For the record though, the removable skids are not necessary in my mind. I didn't include a screw in the render, but the hip joint has a fitting for an m3 machine screw and I'm able to make the joint so tight that you need a considerable amount of force to fold the legs. The removable skids would more be for strengthening the legs for impacts; as a single leg taking the full weight of the Phantom is a dangerous prospect in a crash scenario.

 

[MonsieurAnon]

Just a quick visual update.

Flew it for a bit, landed a lot of times, with 1 hard landing. As predicted the width of the setup made landing more stable, which helped account for the folding nature of the legs. I'm fairly sure that I have a solution for that risk now too, but it will take a little while for me to getting around to implementing it into the design.

 

[OI Photography]

Did that compass mounting (90deg from stock) not give you any problems while flying? I would have it expected it would at least in GPS mode.

 

[MonsieurAnon]

It did actually, I thought I was just overdue for an IMU calibration, but that seems to be a major design problem. Have you fleshed out your idea for feet yet?

 

[MonsieurAnon]

I mocked up some options for feet. The one on the right is an interpretation of a suggestion from OI Photography. The one in the middle is intended to be used in conjunction with 6mm pipe, to create skids.

Please let me know which ones you prefer and if you have any further ideas.

I may be including these as variant options on Shapeways depending on the response that I get.

 

[MonsieurAnon]

Just a quick update to point out that I'm printing and prototyping again. I should have an update tomorrow ... and possible legs for sale, assuming I get a chance to do a test flight.

 

[MonsieurAnon]

So my redesign is nearly complete. It's just down to some minor tweaks of fittings and strength.

Changes I've made:

Triangular struts for strength.
Clip on antenna and compass holders.
Modular / optional feet & struts.
Full plastic design.

 

[MonsieurAnon]

Release candidate test from yesterday.

It flew like a dream. The compass position seems to have been sorted, and landing seemed as secure, if not more so than with the stock legs. I plan to model up some variants to the skids before selling this as a product, but that won't take long as they'll be singular pieces, or push in extensions.

 

[MonsieurAnon]

Without too much fanfare, I thought I'd point out that I'm satisfied with the current release candidate and it's now on sale

Shapeways

Ebay

 

[MonsieurAnon]

I'm also selling a widened version for people with the Universal Camera mount:

http://shpws.me/vbDT

This will be the version that I use in the field.