What is a walker?

[maddox10]

@ Bacon Wizard .
I can't see any reason why it can't be seen as a leg.

[ady]

Why doesn't someone who writes/enforces these rules clarify things?

[Bacon Wizard]

Why doesn't someone who writes/enforces these rules clarify things?

Yes please. For all that some people are saying its no longer worth building one (I don't agree) certainly THIS bit, the uncertainty as to whether all the hard work, time and money will even be permitted to enter... Is the off-putting bit.

[craig_colliass]

Hi Max
I think you have miss understood the point there is no rule, nor has there been any rule about adjusting legs.
The point if you read the post carefully, is to prove the rule about minimum of two degrees of freedom in the walking mechanism.
There are two rules so far to comply for walkers.
1/ the robot must be only supported on it's moving legs.
2/ the mechanism must have at least 2 degrees of freedom.
Supported on legs easy to prove
2 degrees of freedom ????????? how to prove your robot dose this!!!
That's were the adjustment idea comes from if you can separate up/down with forward/backward If you have separated the two you have proved there are two. You have proved the 2 degrees of freedom.
This way you are not dictating motors, cranks, actuators, or any other hardware just functionality.
Hope this clears this up.

Mechadon another fantastic machine. I LOVE this machine but the cruel facts are. that it completely bombed as a combat robot. I think it just about managed half way across the arena before it was completely trashed!!!!!

The gimble type mechanism has the possibility of being able to cope with all 6 degrees of freedom. It is just not likely to survive 30 seconds in a combat environment. to show you what I mean the lifting forks on Cherub HW were 8mm armor plate, the first event they got bent!!

Thanks for all the comments I believe we are making progress.

Craig

[Bacon Wizard]

Oh I wasn't actually proposing to use one.. just asking what people thought of it as what they feel a true walking leg to be (regardless of what the regs actually say)

Yeah, your interpretation of the current regs is the same as mine.


Mechadon is one of my all-time fave bots. Wonderful design, beautiful especially in its movements, innovative.. but a mere ornament for all that.

[daliad100]

For degrees of freedom of a planar mechanism (flat) the Grübler formula:

DOF = 3(n - 1) - 2l1 -l2

Where n = number of bodies (number of links including sliders)
l1 = number of joints with 1 dof (pivot on its own and slider on its own count as one dof)
l2 = number of joints with 2 dof (pivot on a slider)

Should be easy enough to check if a 2d mechanism adheres to the rules.

[craig_colliass]

Thanks
That's great give us some examples. so we can see it working say the Klann walker
http://www.mechanicalspider.com/index.html

[daliad100]

Klann linkage.png

From what I understand about the linkage, it has 5 bars and the background making for 6 bodies, 7 single DOF joints and no 2 DOF joints making for only 1 DOF total.

Hence not a walker by the rules.

I don't think anything that uses a continuously rotating crank as a direct input can have more than 1 DOF otherwise it will be very wobbly and collapse.

​If you guys need any more just say.

[craig_colliass]

Many thanks for that it is always easier to work out these things with an example. perhaps the FRA wil use this calculator for the assessment.

[typhoon_driver]

Although I take it if those legs were on an actuated pivot (as you look vertically down) then they would have the extra degree of freedom required?