pic: 6 wheel omni directional with a suspension

[joeweber]

loading photo ...

[gorrilla]

if your only using two rods it seems that it would not be strong enough and it will be pretty loose you may have a problem with the frame bottoming out

[wilsonmw04]

Can mecanum wheels be backwards as long as the diagonal wheels are in sync?

[EricH]

Originally Posted by wilsonmw04

Can mecanum wheels be backwards as long as the diagonal wheels are in sync?

Yes... but there are some ramifications to that, like it's now easier to spin you around. You may also need to reverse some code for going sideways.

[wilsonmw04]

so what the difference between:

/ \..... \ /
\ /and / \
which is right?
hmm, looking at this again and the left one would tend to turn when the right one wouldn't? Interesting, I never thought of that until I looked at them side by side.

[EricH]

Typically, the "O" pattern is used. The "X" pattern may also be used. (When seen from the bottom; top is the opposite.)

[joeweber]

Originally Posted by gorrilla

if your only using two rods it seems that it would not be strong enough and it will be pretty loose you may have a problem with the frame bottoming out

I am not sure exactly what you are saying far as bottoming out. When we build the robot base it would be secured the length of the rods which are tubes. The base will most likely cover the whole empty area between the drives. We are using tubes (which we may increase the size) so we can slide the bumper bolts into the tubes and than slide pins into them to hold.

http://www.team1322.org/ideas.htm for a side view of the suspension.

[JesseK]

Originally Posted by joeweber

I am not sure exactly what you are saying far as bottoming out. When we build the robot base it would be secured the length of the rods which are tubes. The base will most likely cover the whole empty area between the drives. We are using tubes (which we may increase the size) so we can slide the bumper bolts into the tubes and than slide pins into them to hold.

http://www.team1322.org/ideas.htm for a side view of the suspension.

Rather than increase the size of the tubes, you could also rivet lightweight honeycombed fiberglass or 1/16" sheet aluminum to the bottom, or 6" strips of either. It will greatly increase the rigidity of the two frame segments while also leaving the flex you want for suspension should the tubes not be enough.

This control system is straight up intriguing. The matlab plots are all obscured when the normal unit vector controls are put on it, though I may have the omni wheel's equation incorrect. I hope this succeeds; it will be as fascinating as 'twitch' drive to figure out.

[wilsonmw04]

I'm wondering about how the rest of the robot is going to fit on this frame. As the front arm moves up, won't it force the rest up (and back) as well? I'd be afraid of the CoG with a frame like this. If the center was kept very low, I could see this working.

[Jeff K.]

Along with the previous comment, regarding upperstructures and other things that mount to this, what's going to happen with electronics? Having a flexing board seems like an electronic person's nightmare.
More reasons for it to be an electrical problem than a mechanical or programmers.

[Madison]

What happens to the rod when the front left wheel wants to go up and the front right wheel wants to go down?

[gorrilla]

bottoming out refers to the frame hitting the ground


unless you have enough ground clearance when you accelerate wouldent you frame be so (snakish)? that it would move with every little bump or change in velocity i dont see how you could attach an upper structure to it

[gorrilla]

Originally Posted by M. Krass

What happens to the rod when the front left wheel wants to go up and the front right wheel wants to go down?

good point

[JesseK]

Originally Posted by gorrilla

... that it would move with every little bump or change in velocity i dont see how you could attach an upper structure to it

The manipulator mount problem is easy in concept to solve, but it adds weight. The main base of the manipulator would have to be fully supported by one of the frame segments (forward or rear) and the angled supports that attach to the opposite frame segment would have to be broken up into two parts that attached to a gas shock or compression spring in a "Y" formation. So rather than seeing one solid bar for the angle support, we would see a "Y" with the compression spring/shock forming the base of the Y. Note, not a "T" formation because a "T" wouldn't allow the frame to flex up and down.

CoG and stability would have to be tweaked, but it is definitely possible.

[joeweber]

The rods are pivot points only and do not move or flex. A base of the main part of the robot will be attached to the rods. The rods are only showed to tie the two halves together. The rods only need to be long enough to go from the base through the drive units to allow for the pivot. When built we would limit the amount of pivot needed for any ramps required. We could also connect pneumatics to lock down the suspension for any long reaching manipulator. View http://www.chiefdelphi.com/media/photos/31755 to get a better understanding of how the base would attach to the rods. One half of the drive unit has slots to alow for the movement of the suspension. If you look close at the drowing you can see the slot and hole.