Scuttle - 4DOF Hexapod

Lynxmotion Legged Robots
1

Hi roboteers!

I have been working on a new hexapod for a few weeks now, and this morning the final parts of the puzzle arrived.

So this is my new 4 DOF Hexapod - Scuttle
As it is rather different to most hexapods I will break its design down into components.

*Ignore the messy wires. But I’ve got a lot of work left

Body

The body is made of five plates spaced with Hex stand-offs.
It houses 6 Servos which give the extra DOF over a standard hexapod.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00085.jpg

Down the Center plate there are brackets that brace the Hips

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00086.jpg

On the under side is a void for the electronics and battery.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00088.jpg

Hips

Made from interlocking plates braced with Hex stand-offs.
For these pictures the rear plate has been swapped with another front plate.
When assembled correctly its the rear that attaches to the center body plate.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00084.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00083.jpg

Assembled Body and Hips

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00102.jpg

The following pictuires show the Hips twisting in a couple of different directions.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00106.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00105.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00103.jpg

Leg’s

Femur’s

In a change to the norm I have decided to mount the Knee servo on the Femur.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00095.jpg

The double plated Femur id held stable wih a rear bearing.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00096.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00098.jpg

Another reason this hexapod is different to most is that the Front, Middle and Rear legs are all of differing lengths.
This can be seen below, Front, Middle Rear respectively.
As welll as the Legs being different lengths the hips are at different heights as well.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00099.jpg

Tibia’s

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00089.jpg

The double plated Tibia is held stable wih a rear bearing.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00091.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00093.jpg

Here you can see the differing lengths of Tibia. Front, Middle and rear respectively.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00094.jpg

Assembled Leg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00101.jpg

The Inside curve of the Tibia is matched exactly with the outside curve of the Femur.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00100.jpg

Full Assembly

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00112.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00113.jpg

Side on with legs spread.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00117.jpg

Side on with legs aligned

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00121.jpg

A repeat of the hip rotations with the legs attached.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00130.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00122.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00126.jpg

As well as the Hardware redesign I have been rewriting my Hex Code. its about 70% complete.
But it will have;

6 Dof Body transformations with control of the location of the point of rotation
3 Dof Locomotion with five speed ccontrollable gaits

  • Tripod
  • Wave
  • Ripple
  • Quadripple
  • Scuttle - My own gait designed to show off the fact the legs are different lengths )
    Single Leg and Dual leg control.
    PS3 six-axis and Android Input devices

I also have a pan/tilt head with mandables on the way.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00131.jpg

Please let me know what you think. :smiley:

2

wow. very cool and unique. i like custom builds and this fits into the top category.

i like the idea you have used for the extra DOF. That extra rotation will give you some very interesting gaits, and may even allow for climbing.

very cool idea. and a very interesting project
8)

well done.

those tibias look very cool. and the legs close in very nicely.
keep up the good work. :wink:

3

Quite a project! I second Jonny’s appreciation of the efforts!

Looking forward to the video.

Alan KM6VV

4

What a beautiful solution! Both unique and functional.

I’m working on a hexapod with a similar design! Not 4DOF, but with the innermost joints rotated the same way (they are arranged in a circle though, so the body is cylindrical :slight_smile: ). Really intresting to see how you solved it.

Looking forward to updates!

5

Hi,

Very interesting and unique design! I’m very interested to see how you are planning to implement the 4. DOF into the kinematics. It sure opens for some cool body movements and different leg configurations. But whats your main goal by adding the 4. DOF?

I wish you good luck with the code and I can’t wait to see it move! :smiley:

6

Thanks guys for the complements!

Im looking forward to seeing your cylindrical hexapod!
An idea Ive always liked is a hexapod with legs that when retacted form a sphere.

Update - Most of my Pan/Tilt and Mandables arrived this morning. I just need to make a braket to join the head to the neck.
As with the rest of the robot they are designed rather differently.

This is the Head.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00141.jpg

It contains two HS 225BB’s. The Top servo controls the Pan via an offset gear. It gives roughly +/-35 degrees of rotation.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00149.jpg
http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00150.jpg

The Lower servo controls the mandables.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00157.jpg
http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00158.jpg

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00159.jpg

The Neck. Due to the vertical body plates, the raduis of the front of the body and the mountings for the hips,
the neck was an interesting challange to design.

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00169.jpg

From the pictures it is hard to tell how it is mounted so bellow is a CAD drawing.

http://i291.photobucket.com/albums/ll284/blobbington/Untitled-1.jpg

The servo is mounted in a cradle that is suspended/rotates around the same point as the front hips.
Then the servo horn is geared onto the body. this gives +/-90 degrees

http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00162.jpg
http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00163.jpg
http://i291.photobucket.com/albums/ll284/blobbington/Scuttle/DSC00166.jpg

7

Very interesting and creative gearing for the jaw and neck!

Looks like you’ve had some ME training…

Alan KM6VV

8

Yay, progress :smiley:

Your mechanical solutions inspires me very much!

What material are you using btw?