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18 DOF High-Flotation Hexapod Robot

Six legs, 18 servos, with optional high-flotation mode. My first project that combined robotics and 3D printing.

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I looked around on the interweb for spider-ish robot designs but mostly what I found was robots with 2 degrees of freedom (or less) per leg. A lot of them didn't look like spiders and some of them didn't look very useful. This project was started to design a spiderish robot with 18 degrees of freedom and the power of omni-directional movement.

This 3D-printed hexapod robotic platform frame was designed and built from the ground up. It measures about 20" (50 cm) from leg tip to leg tip. Designed around the nylon gear sg90 servo form and re-designed around the mg90 (metal gears), it is ready for servos, a servo control board, power supply and supporting software/controllers. Use the built-in hardware assembly options (screws) or opt for a 90% zip-tie build!

Intended to operate as both a typical 18 degrees of freedom hexapod with omnidirectional motion capabilities, it also has a 'high-floatation' mode with 12 degrees of freedom. The larger surface area is provided by the end segment of the leg laying flat on a surface like snowshoes or flippers.

This frame and motors kit is available on my Tindie page - http://bit.ly/hex_Ken_do

  • 18 × SG90 9g servo
  • 1 × 3D printed frame This frame is available on my Tindie page - http://bit.ly/hex_Ken_do
  • 1000 × Zipties/zapstraps Not really that many, but a bunch

  • Sensors

    ken.do09/29/2017 at 19:29 2 comments

    This is a list of possible sensors for inclusion

    Gyro - ideally, this robot should be able to walk on a grade and maintain the upright orientation of the hub. Useful for side-grades and inclines, keeps camera or other equipment on the level.

    Optical flow sensor - this would allow the robot to track actual movement (for measuring slippage and closely estimating location)

    Pressure sensor - incorporated into the leg joint(s) to signal ground/other contact and with the appropriate sensor, measure amount of force applied to each 'foot'

    Ultrasonic distance sensors - for obstacle avoidance and relative positioning

    Camera(s) - also for obstacle avoidance and relative positioning, (obstacle recognition?)

  • Build - Step 7

    ken.do09/03/2017 at 00:40 0 comments

    7. Route cables

    Now all that is left is hooking your servos up to a control board. Battery and control board mounting configuration is up to you!!

  • Build - Step 6

    ken.do09/03/2017 at 00:40 0 comments

    6. Attach foot to mid leg

    Using the shallower nub, follow the procedure for attaching the mid leg to the hip. it is important that the rounded part of the foot is up relative the top of the main body.

    Again, seat and secure horn to both servo and foot.

  • Build - Step 5

    ken.do09/03/2017 at 00:39 0 comments

    5. Attach mid leg piece to hip joint

    Insert the fat end of one of the deeper nubs into the bottom of the mid leg piece. Repeat the procedure for attaching the hip joint to the main body, but using the mid leg piece instead of the main body. Don't forget to seat the horn on the servo and attach to both the servo and the hip joint. (I didn't attach to hip joint because I ran out of screws!)

  • Build - Step 4

    ken.do09/03/2017 at 00:39 0 comments

    4. Assemble mid leg pieces

    Again, insert servo bottoms (both at once) into the receptacles on the mid leg piece, being careful to avoid pinching the control wires. Then place and secure the other half using either zip ties or screws.

  • Build - Step 3

    ken.do09/03/2017 at 00:39 0 comments

    3. Add hip joint to main body frame

    Insert a nub with the deeper wide section, narrow section first into the inside of joint.

    The main body frame has a bevelled section for the nub end to slide up and into place. Insert and attach servo horn onto the hip joint, flat side out, seating it securely to the hip and the servo in the main body. I used the screws provided with the servos, but needed to drill out one of the horn holes to accomodate the screw size.

  • Build - Step 2

    ken.do09/03/2017 at 00:38 0 comments

    2. Assemble the 'hip' sections

    Two identical hip sections are placed together 90 degrees from each other.

    Attach them through the center hole with a 4mm x 1/2 inch-ish machine screw and nut.

  • Build - Step 1

    ken.do11/24/2016 at 22:15 0 comments

    *note* The longer nubs may not be necessary any more due to tighter printing tolerances. If the shorter nubs work, use them in place of the longer ones.


    1. Assemble the main body frame:

    To assemble the main body frame, servos are inserted in each of the 6 receptacles on one half of the frame and then sandwiched with the other half. Secure the halves with zip ties, or screws.

View all 8 project logs

  • 1
    Step 1

    *note* The longer nubs may not be necessary any more due to tighter printing tolerances. If the shorter nubs work, use them in place of the longer ones.


    Assemble the main body frame:

    To assemble the main body frame, servos are inserted in each of the 6 receptacles on one half of the frame and then sandwiched with the other half. Secure the halves with zip ties, or screws.

  • 2
    Step 2

    Assemble the 'hip' sections

    Two identical hip sections are placed together 90 degrees from each other.

    Attach them through the center hole with a 4mm x 1/2 inch-ish machine screw and nut.

  • 3
    Step 3

    Add hip joint to main body frame

    Insert a nub with the deeper wide section, narrow section first into the inside of joint.

    The main body frame has a bevelled section for the nub end to slide up and into place. Insert and attach servo horn onto the hip joint, flat side out, seating it securely to the hip and the servo in the main body. I used the screws provided with the servos, but needed to drill out one of the horn holes to accomodate the screw size.

View all 7 instructions

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Discussions

Gert Galjoen wrote 08/03/2017 at 08:07 point

Great design, did you manage to control it already?

  Are you sure? yes | no

David H Haffner Sr wrote 04/22/2017 at 22:33 point

Ha, I like this little fella :)

  Are you sure? yes | no

ken.do wrote 03/24/2017 at 14:32 point

I haven't tried programming yet (not my strength). For the brains, there are a lot of good Arduino control sketches, so I will probably try to go that route with a Nano or Mini. And then try one of the LynxMotion servo control boards. Power will be supplied by a 2s Lipo (capacity to be determined by where I can fit it).

  Are you sure? yes | no

deʃhipu wrote 03/28/2017 at 14:09 point

If you didn't make it walk, how did you know what proportions of the leg segments and what angles would be optimal?

  Are you sure? yes | no

ken.do wrote 03/28/2017 at 14:18 point

I researched similar bots and looked at some theory. I will fine tune with trial when control is established.

  Are you sure? yes | no

deʃhipu wrote 03/24/2017 at 14:06 point

Very nice! What are you plan to use for the brains? And for the power? Did you already try to program it to walk?

  Are you sure? yes | no

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