View Full Version : pic: Ramp Video
joeweber
02-01-2009, 11:07
[cdm-description=photo]32185[/cdm-description]
Tottanka
02-01-2009, 11:08
WOW!
Very nice guys! Congratulations on that amazing drive!
joeweber
02-01-2009, 15:30
Heres a quick link to the video
http://www.youtube.com/watch?v=xby0SOphLUg&feature=channel_page
I should have had it go sidways more to show that the ball differnetal works but if you look close at the start it goes sideways.
Cyberphil
02-01-2009, 16:03
Awesome! In the video, you could have made the plastic a little more sturdy. But it still made it up, amazingly easy. Great job!
It is SO cool. I really hope to see this on your competition bot. Should be interesting to see how you end up mounting a manipulator on it.
are those chains i see going to the omni wheel in the middle? if so have you had a problem with them falling off?
I remember admiring the design for this... good to see it came out so well!
FlyingHedgeHog
14-01-2010, 19:27
Uh... Section 8, R11 The FRAME PERIMETER must be comprised of fixed, non-articulated structural elements of the ROBOT. The FRAME PERIMETER must remain a fixed, unchanging polygon throughout the MATCH.
http://usfirst.org/uploadedFiles/Community/FRC/Game_and_Season__Info/2010_Assets/08_The%20Robot_RevA.pdf
Sorry guys, we had the same idea...
Chris is me
14-01-2010, 19:31
Uh... Section 8, R11 The FRAME PERIMETER must be comprised of fixed, non-articulated structural elements of the ROBOT. The FRAME PERIMETER must remain a fixed, unchanging polygon throughout the MATCH.
http://usfirst.org/uploadedFiles/Community/FRC/Game_and_Season__Info/2010_Assets/08_The%20Robot_RevA.pdf
Sorry guys, we had the same idea...
I wonder if you could mount a FRAME around an articulating drivetrain. Since at least two of the wheels will be touching the ground at any one time, the BUMPERS could be mounted to the back of the suspension in a fixed manner... I think they have ways of legally doing it.
maltz1881
14-01-2010, 19:34
That isn't the frame of our robot though.. so we are perfectly safe.::D Our frame won't have a suspension.
FlyingHedgeHog
14-01-2010, 20:06
That isn't the frame of our robot though.. so we are perfectly safe.::D Our frame won't have a suspension.
FRAME PERIMETER – the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string describes this polygon.
FlyingHedgeHog
14-01-2010, 20:08
FRAME PERIMETER – the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string describes this polygon.
I think the judges would frown on that, it's kind of lawyer-ing, you know? I mean, the point of that Rule R11 is to prevent you from doing that. I don't think you should do it, as much as I would LOVE to...
Nuttyman54
14-01-2010, 20:50
I think the judges would frown on that, it's kind of lawyer-ing, you know? I mean, the point of that Rule R11 is to prevent you from doing that. I don't think you should do it, as much as I would LOVE to...
This picture was posted a year ago as a prototype concept. It may or may not have any bearing on what team 1322 is doing this year.
...not that it wouldn't be pretty awesome to see in competition...
DonRotolo
14-01-2010, 22:09
This picture was posted a year ago
Words worth repeating.
joeweber
15-01-2010, 07:33
As you can see from the drawing the frame is stationary on level ground and does not articulate. When it goes over the ramp the drive system articulates but the frame remains solid. ( the frame is where the bumpers are attached).
http://www.team1322.org/2010DRIVERAMP.JPG
GaryVoshol
15-01-2010, 08:30
Joe, it seems to me that as the middle wheel goes up, the outer wheels go down. Wouldn't this cause the bumper height to change? Bumpers must remain in the BUMPER ZONE, 10-16" off a level surface.
Rosiebotboss
15-01-2010, 08:34
Joe, it seems to me that as the middle wheel goes up, the outer wheels go down. Wouldn't this cause the bumper height to change? Bumpers must remain in the BUMPER ZONE, 10-16" off a level surface.
Key phrase--"level surface". If the robot is set up on a level surface, are the bumbers in the bumper zone?
betsy888
15-01-2010, 11:06
Looks like your center wheels are 2 individual omni wheels per side, each one slaved to either the fore or aft mecanum wheel. So basically the center wheels are commanded to have the same velocity profile as the front/back wheels. Is this accurate? :confused:
btw, awesome design and thanks for sharing your ideas. We're a second year team so still need lots of help!
Chris is me
15-01-2010, 11:16
Looks like your center wheels are 2 individual omni wheels per side, each one slaved to either the fore or aft mecanum wheel. So basically the center wheels are commanded to have the same velocity profile as the front/back wheels. Is this accurate? :confused:
There's a ball differential so if the front and back wheels are spinning in opposite directions, the omnis don't turn.
FlyingHedgeHog
15-01-2010, 16:46
This may sound a tad bit pompous but that seems like lawyering to me. The way we look at it is: What's the purpose of the rule? What is it trying to stop us from doing?
Last year, there was a robot that had fans on the bottom of it at the Portland regional. The idea was to suck it down to the floor in order to gain more traction. The judges didn't let it slide and the team ended up with a box on wheels. I'm not trying to be a rules Nazi, I just think the judges won't let it pass and you'll be in some serious trouble...
Chris is me
15-01-2010, 16:53
This may sound a tad bit pompous but that seems like lawyering to me. The way we look at it is: What's the purpose of the rule? What is it trying to stop us from doing?
Last year, there was a robot that had fans on the bottom of it at the Portland regional. The idea was to suck it down to the floor in order to gain more traction. The judges didn't let it slide and the team ended up with a box on wheels. I'm not trying to be a rules Nazi, I just think the judges won't let it pass and you'll be in some serious trouble...
That specific robot design was ruled illegal by the GDC in the Q&A weeks before the competition.
The Q&A is the only way to figure out answers to designs like this.
Brad Voracek
15-01-2010, 17:56
You also have to watch out for your max height.
Don't make the robot 5 feet above the frame, make it 5 feet above the wheel at the lowest point.
How they would test this in the box.. I don't know.
But still, ask the Q&A if you guys go with it. Awesome drive.
joeweber
17-01-2010, 21:49
Joe, it seems to me that as the middle wheel goes up, the outer wheels go down. Wouldn't this cause the bumper height to change? Bumpers must remain in the BUMPER ZONE, 10-16" off a level surface.
<r07>The BUMPERS must be located entirely within the BUMPER ZONE when the ROBOT is standing normally on a flat floor,
The measurement is taken when the robot is on flat floor. We meet all requirements that we have found in the rules. The bumpers are between 10 an 16 inches above the floor when on flat ground.
If I was an inspector, I would measure your robots bumpers with all wheels in contact with the floor . Then I would ask you to full articulate the wheels and then measure the bumpers. If at both configurations the bumpers where with in the bumper zone then I would be satisfied. If not then I would turn this down. I am not an inspector nor am I a member of the GDC. You better Q & A this soon before you go farther. From the picture your bumper height appears to be variable and not fixed or static.
If I was an inspector, I would measure your robots bumpers with all wheels in contact with the floor . Then I would ask you to full articulate the wheels and then measure the bumpers. If at both configurations the bumpers where with in the bumper zone then I would be satisfied. If not then I would turn this down. I am not an inspector nor am I a member of the GDC. You better Q & A this soon before you go farther. From the picture your bumper height appears to be variable and not fixed or static.
Sure looks like bumper height would remain fixed while on the flat floor as the regs require.
Everyones bumpers will be out of the bumper zone when going over a bump, so if this thing is legal on the floor it seems fine to me.
If the robot is flat on the floor and the middle wheel is articulated up, are the bumpers still in the bumper zone? This really needs a Q&A. Also with the bumpers up high this year, robot frames will be subjected to allot more stress than in past years with the low riders. Make sure those supports are robust.
joeweber
18-01-2010, 10:50
If the robot is flat on the floor and the middle wheel is articulated up, are the bumpers still in the bumper zone? This really needs a Q&A. Also with the bumpers up high this year, robot frames will be subjected to allot more stress than in past years with the low riders. Make sure those supports are robust.
If the robot is on the flat floor why would the wheels be articulated up? The articulation is not powered. the wheels follow the floor all the time.
maltz1881
18-01-2010, 12:03
The center Omni's are ALWAYS touching the ground, they never leave the floor. They aren't powered by anything other than the friction on the carpet when the Mec wheels are moving. The bumpers are in a permanet position. If you use the bump to manuvere around the field then no matter what your bumpers are going to change height. Meaning when you are going up your back bumper will be closer to the ground then if you were on level ground and just the opposite when going down the other side. The bumpers are solid and in the correct height while on LEVEL ground!
We have read the rules many many times and the question has been given to Q & A. We have asked many many teams in our area about it and if this is doable. Most agree with us that it is perfectly fine while others weren't sure. We are 99.9% sure that we are correct and would be shocked to see anything differently.
joeweber
19-01-2010, 21:55
Q & A gave us the green light, Yahooo!!!
Yep Joe, Update #3 today also green-lighted it. I really look forward to seeing this design in action! Be sure to post some videos of it during competition.
betsy888
20-01-2010, 09:32
There's a ball differential so if the front and back wheels are spinning in opposite directions, the omnis don't turn.
Thanks so much for the feedback. Our team has decided against having an articulating 6-wheel approach due to the complexity and the limitations of our team but I must say I'm still curious. How does your ball-differential work? From what I understand of ball differentials, there is one drive gear and 2 driven axles. So I assume your center omni wheels are on the driven axles. But you have 2 driving chains coming from the omni wheels and only one drive gear. Do you have a special type of ball differential? Can you explain a bit more?
Thanks again! Good luck with your design. Congrats on getting the green light in Q&A!!
joeweber
20-01-2010, 09:47
How does your ball-differential work? From what I understand of ball differentials, there is one drive gear and 2 driven axles. So I assume your center omni wheels are on the driven axles. But you have 2 driving chains coming from the omni wheels and only one drive gear. Do you have a special type of ball differential? Can you explain a bit more?
The Mechanum wheels are driven, the chains drive sprokets on the ball differential, between the sprockets are steel balls that are inside a round flange with holes for the balls. The flange is attached to the drive shaft with the omni wheels. Pictures are on our wesite http://www.team1322.org/ideas.htm
http://www.team1322.org/Ball%20differential.JPG
Is that the 45degree angle of the ramp? it looked to shalow, and you should build a real bump if possible because it is much harder to test with out the real thing if you know what i mean.
joeweber
20-01-2010, 10:08
Is that the 45degree angle of the ramp? it looked to shalow, and you should build a real bump if possible because it is much harder to test with out the real thing if you know what i mean.
That picture is from one year ago. You can view a video http://www.youtube.com/watch?v=jQMcw4QNCLI
The video ramp is a 45 degree ramp but we had to cut the corners for the low ground clearence of the 6 inch wheels. We will be using 8 inch
DynamiteHack
20-01-2010, 11:07
As you can see from the drawing the frame is stationary on level ground and does not articulate. When it goes over the ramp the drive system articulates but the frame remains solid. ( the frame is where the bumpers are attached).
http://www.team1322.org/2010DRIVERAMP.JPG
Correct me if I'm wrong, but wouldn't the sections connecting the omnis to the mountings have to get longer/shorter as it tilted? Adding height to the slope gives a longer line.
Unless the mountings can tilt in and out?
joeweber
20-01-2010, 11:39
Correct me if I'm wrong, but wouldn't the sections connecting the omnis to the mountings have to get longer/shorter as it tilted? Adding height to the slope gives a longer line.
Unless the mountings can tilt in and out?
The rear virtical strut will pivot at the frame.
betsy888
20-01-2010, 21:44
[QUOTE=joeweber;902964]The Mechanum wheels are driven, the chains drive sprokets on the ball differential, between the sprockets are steel balls that are inside a round flange with holes for the balls. The flange is attached to the drive shaft with the omni wheels. Pictures are on our wesite http://www.team1322.org/ideas.htm
I think I know the source of my confustion. I assumed the omni wheels could move independent of each other. Now that I see your ball differential drawing and photos it looks like they are attached to the same shaft so must move together. If this is true, why do you have 2 omni wheels at each location, why not just one?
As always, thanks and good luck!
If this is true, why do you have 2 omni wheels at each location, why not just one?
It provides a smoother ride than having one single omni at each point. A number of teams have tried single; I believe most of them switched to double at some point.
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