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New 2 DOF Leg design.

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Posts: 9258
Posted: 2010-06-16 15:30 
 Post subject: New 2 DOF Leg design.
Well I found a cool use for the new ASB-25's (They will be available on the new website very soon.) I'm using it as the femur on this new leg design. As with any mechanical advantage leg design it has the normal pro's and con's.

Pro's
  • Absolutely no power required to hold the body up with the legs lowered.
  • Inexpensive servos can be used.
Con's
  • There is a limit to the legs up position angle that can be achieved. There is a point of no return on the pushrod. Go too far and the servo will not be able to pull the leg into the down position.
  • Its use is normally restricted to 2DOF legs.

As you can see in the first image. The mechanical advantage is when the forces on the lift/lower servo are not rotational, but in-line with the servos output shaft. This works very well and is very strong!

The second image is with the leg lifted. The throw is about 2.25" which is pretty good for this style of walker. I added a Hex Standoff to prevent the leg from going past the point of no return. Even though the design allows the use of inexpensive servos, its use of the ball bearing hinges will increase the cost. We need to make an inexpensive injection molded equivalent.

The third image is from the top. It shows how well the end of the tibia lines up with the horizontal axis servo.

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The last thing I will mention is that the SSC-32 has a built in 12 servo sequencer. You can control the entire walking process for all 12 servos with a hand full of very simple commands. Old school 12 servo hexapods are cool too! lol :D

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Jim Frye, the Robot Guy
http://www.lynxmotion.com
I've always tried to do my best...


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Posts: 3298
Posted: 2010-06-16 16:12 
nice idea jim, a better improvement in using the mechanical advantage bracket than previously seen. yes iv always loved the 12 servo hexapods. this leg would look great with another 5 built up and shoved onto the mini hex chassis. :wink:

your right the coxa axis does line up very well.
Another great addition to the SES leg line. 8)
and its also a great advantage that beginners can use the built in hexapod generator while still having a complex-ish ,cool looking robot.

i like it. :wink:

_________________
Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk
Create, Innovate, Inspire.


User avatar
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Posts: 9258
Posted: 2010-06-16 16:23 
Thanks for the comments Jonny. PS your tracking number will be mailed to you later today. ;)

_________________
Jim Frye, the Robot Guy
http://www.lynxmotion.com
I've always tried to do my best...


User avatar
Guru ( offline )
Posts: 3298
Posted: 2010-06-16 17:17 
yes thanks jim. Scheduled Delivery: 18-June-2010! just got email. im clearing the desk now. 8) :D

_________________
Jonny Poole,
Freelance Concept Art & Animatronics, 3D Art and 3D Modelling, as well as Physical Modelling, Mechanical design, and illustration.
http://www.innerbreed.co.uk
Create, Innovate, Inspire.


 

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