degrees of freedom...

[kutalinelucas]

Hey Guys. Just have a quick question, if a robot hand was actuated by 9 motors, one for each base knuckle and then one motor to actuate the medial and distal knuckles on each finger, this makes the device underactuated right? so it would have 9 degrees of actuation, 13 joints, but how many degrees of freedom?

I've found some conflicting stuff...some sources refer to a degree of freedom as the number of independant displacements which provide the kinematic characteristics, but as the medial/distal knuckles engage linearly, the motion of both coupled joints define the hand's characteristics...

So basically...could I present my hand as having 13 degrees of freedom?...sounds much cooler than 9!

Any input would be brilliant

Martyn

[Elijah5647]

I would say that because you can only control 9 different positions then it is only 9 DOF but then again if you can't see how many motors there are than you could easily say that its 13DOF. Its your choice.

Cheers
Elijah

[kutalinelucas]

Well its for my Msc robotics thesis which I'm presenting to a bunch of people who really know about this stuff next week...so I should really be sticking to nine then

Thanks for the input

[Soeren]

Hi,

[...] if a robot hand was actuated by 9 motors, one for each base knuckle and then one motor to actuate the medial and distal knuckles on each finger, this makes the device underactuated right? so it would have 9 degrees of actuation, 13 joints, but how many degrees of freedom?

Assuming a humanoid (i.e. 5 fingers) hand...
"one for each base knuckle" = 5
"one motor to actuate the medial and distal knuckles on each finger" = 5 more

Don't see how you get to 9?

If each finger is more or less parallel, it could be debated whether they actually was only one DoF per joint-"type", i.e. 3 in all.