Monday, August 27, 2018

Mojo (#13) - Knobby Knees

I am still investigating the best leg design for Mojo - The compliant quadruped walking robot.  It is clear from the videos that perhaps the legs are "too compliant". The springs are showing some compression, even as the robot stands. Also, in the configuration, the robot can not handle the weight of the battery without further compression. 
Mojo - The Compliant Quadruped Walking Robot - with sexy robot legs
I believe when the knee servo pulls the leg up, the robot is not gaining much more additional compression. In addition, when the leg is moving back in the gait, the leg also compresses.  So, it seems, I will need either stronger/tunable springs or perhaps a 'less compliant' compliant leg.

So, we iterate through a different design! The new design that will allow for the leg to be pulled back, with out compliance.  But, still have the ability to be compliant when the knee is flexed and absorb some ground shock.

Straight legs with "knee joint" - 3D printed
The new legs are straight, with a "knee cap", and the Serial Elastic Actuator (SEA) is located on the back. Unfortunately this design does not have much in aesthetic appeal. - They are ugly!!

Mojo - A Compliant Quadruped Walking Robot - now with "knobby knees"
Hmmnnn...  I am not sure if I like this tangent in the design. The knees perform better in the standing position. Walking is still very unstable. The new actuators do not have much clearance Unfortunately, this design experiment did not yield good results!  Such is prototyping.

Back to the Drawing Board!!

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