Hello All,
What are the advantages of using the LPA vs directly connecting a bracket or hub to the servo horn ? Please advise.
I am looking to use hip servos to rotate the legs - so was thinking do I really have to use the LPA or can I directly connect the leg bracket to the hip servo.
Please help
Thanks
The Low Profile Axis is really intended to be used to add rotation to a joint such as in the images below. If you are designing a leg, it’s not really necessary at all. Just ensure that whichever servos you choose can handle the torque.
Thanks CB! I had seen the archer design and that was using the LPA.
I am using 645MG for now - should be good I think. Current config is more of a hip lift - orientation like the biped torso - so the leg can move in or out. This I am thinking of converting to a rotate.
I have no clue about intergrating a hip rotate in to the movement subroutines in the auto walk brat programs - so that would be a challenge!
Again thanks!
BTW - even for the above rotate why not use a direct connection to the servo horn ? Just wondering.
It would make for very cool, and more organic walking indeed.
If it was connected directly to the servo, all the weight of the lower arm would be on the servo’s final output gear; It’s not good to put too much radial weight on a servo spline, plus it’s not a tight fit radially so the lower arm would sag. You could do a direct connection only if the lower arm is somehow supported another way.
OK I understand the issue now! With the hip rotate it would be that the spline would be pointing down or up but not sideways - so the lever moment may be minimum or none!
I saw in Archer the LPA is used but the servo is still straight up so may be the LPA is there for gearing.
The LPA is a 1:1 gear ratio. It’s really there to take the stress off the servo’s final output gear and ensure the connections are straight.
