OCCRA
Go to Post Enlighten a man who sometimes has difficulty understanding why others stray outside the box, when the box appears to be an optimized and elegant solution. - JVN [more]
Home
Go Back   Chief Delphi > Technical > Technical Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 08-29-2005, 11:40 AM
Andrew Blair's Avatar
Andrew Blair Andrew Blair is offline
SAE Formula is FIRST with Gasoline.
FRC #0306 (CRT)
Team Role: Alumni
 
Join Date: Feb 2005
Rookie Year: 2004
Location: Corry
Posts: 1,193
Andrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond repute
Send a message via AIM to Andrew Blair Send a message via Yahoo to Andrew Blair
Lightbulb Robot Adaptive Suspension

I have been throwing around the idea of an adaptive suspension system for a robot for a while now, and I don't know whether or not to invest the time and effort into designing one. The idea behind is to cancel out as much swaying as possible on a top heavy bot, to keep it steadier while driving, and while scoring things requiring precise alignment. The 2005 game was a great example. Level playing field, no obstacles, but you have fast moving play while carrying a heavy object high in the air. And as always, people trying to hit you while you're trying to score. I was considering a 4 wheel drive, with short pneumatic cylinders on each wheel. If you can control each wheel, I believe that you can cancel out much unwanted movement. I got the idea from the Bose suspension, Here .
__________________
Reading makes a full man, conference a ready man, and writing an exact man.
-Sir Francis Bacon

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction."
-Albert Einstein
  #2   Spotlight this post!  
Unread 08-29-2005, 11:46 AM
phrontist's Avatar
phrontist phrontist is offline
Proto-Engineer
AKA: Bjorn Westergard
FRC #1418 (Vae Victus)
Team Role: College Student
 
Join Date: Feb 2004
Rookie Year: 2004
Location: Falls Church, VA
Posts: 828
phrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond repute
Send a message via AIM to phrontist
Re: Robot Adaptive Suspension

I've given it some thought, but I think the major issue would be controlling the pneumatics quickly. I'm assuming you mean some sort of active cancellation system, which detects swaying and adds pressure to the correct cylinders appropriately. If this is the case, I think you would have issues implementing this, as there is currently no way (that I'm aware of) to multiposition pneumatics over short distances or regulate pressure in cylinders.

If you really wanted to, you could attach a strip with black and white quaderature pattern on it to your pneumatics and rig up banner sensors to figure out their position in real time...

Seems like a lot of work/weigth/complication for very little benefit.
__________________

University of Kentucky - Radio Free Lexington

"I would rather have a really big success or a really spectacular crash and failure then live out the warm eventual death of mediocrity" - Dean Kamen
  #3   Spotlight this post!  
Unread 08-29-2005, 11:57 AM
Andrew Blair's Avatar
Andrew Blair Andrew Blair is offline
SAE Formula is FIRST with Gasoline.
FRC #0306 (CRT)
Team Role: Alumni
 
Join Date: Feb 2005
Rookie Year: 2004
Location: Corry
Posts: 1,193
Andrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond repute
Send a message via AIM to Andrew Blair Send a message via Yahoo to Andrew Blair
Re: Robot Adaptive Suspension

Well, I was going to use a couple gyro chips and pressure only the correct cylinders to cancel the motion. So instead of posistioning the cylinders to an exact position, the cylinders pressurize till the acceleration is canceled. However, the more I think about, a never ending seesaw effect could ensue. That would be interesting to watch...
__________________
Reading makes a full man, conference a ready man, and writing an exact man.
-Sir Francis Bacon

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction."
-Albert Einstein
  #4   Spotlight this post!  
Unread 08-29-2005, 12:13 PM
phrontist's Avatar
phrontist phrontist is offline
Proto-Engineer
AKA: Bjorn Westergard
FRC #1418 (Vae Victus)
Team Role: College Student
 
Join Date: Feb 2004
Rookie Year: 2004
Location: Falls Church, VA
Posts: 828
phrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond reputephrontist has a reputation beyond repute
Send a message via AIM to phrontist
Re: Robot Adaptive Suspension

Quote:
Originally Posted by Andrew Blair
Well, I was going to use a couple gyro chips and pressure only the correct cylinders to cancel the motion. So instead of posistioning the cylinders to an exact position, the cylinders pressurize till the acceleration is canceled. However, the more I think about, a never ending seesaw effect could ensue. That would be interesting to watch...
Well what you'd want to use here is some sort of PID feedback loop (then again, that's my answer to everything ). Properly "tuned" you could avoid said oscillation. I don't think the code would be too bad, it's the mechanics that wouldn't work out.
__________________

University of Kentucky - Radio Free Lexington

"I would rather have a really big success or a really spectacular crash and failure then live out the warm eventual death of mediocrity" - Dean Kamen
  #5   Spotlight this post!  
Unread 08-29-2005, 01:09 PM
Gui Cavalcanti's Avatar
Gui Cavalcanti Gui Cavalcanti is offline
Robogeek
no team
Team Role: College Student
 
Join Date: May 2001
Rookie Year: 2001
Location: Needham, MA
Posts: 224
Gui Cavalcanti is a name known to allGui Cavalcanti is a name known to allGui Cavalcanti is a name known to allGui Cavalcanti is a name known to allGui Cavalcanti is a name known to allGui Cavalcanti is a name known to all
Send a message via AIM to Gui Cavalcanti
Re: Robot Adaptive Suspension

The Bose suspension uses 4 high-power electric linear motors in place of a spring/damper suspension system. The system uses the equivalent of 1/3-1/2 the power of an air conditioner, even if you're on a level road. It took several years to develop to the point where it was appreciably more useful than a spring/damper system.

If you want to talk about controlling sway and body roll, you need actuators that can precisely control the force exerted by each wheel upon the ground. A positional actuator (FIRST's use of pneumatics, for binary positions) would be really hard to implement. In order to do it well, I think you would need the pistons on each wheel and 4 software-adjustable pressure regulators with a reaction time in the millisecond range.

I think a nifty, doable idea would be to build a suspension for a FIRST robot, with a small motor (globe, window) that compresses or releases a coil spring to provide variable stiffness to each wheel. I'm pretty sure it is within the realm of easily available FIRST components.

If you want more information on this type of actuator, I would suggest Googling "adjustable compliance" actuators. There's some really nifty stuff being done in the world of legged robots that is very similar to what you're describing.

As a final thought, a lot of the jerkiness I saw with FIRST robots at the Capitol Clash wasn't caused by other robots, but by the robot's drivetrain. Differential drive systems (tank steering) are generally driven in a start-stop-turn manner, which introduces all sorts of weird accelerations that can cause a robot to tip over or lose its load (i.e., throw a tetra into the crowd). A good mechanical solution to this might be to switch to ackerman steering (car-style) due to its inherent stability, and have a control system that limits motor acceleration.
__________________
Gui Cavalcanti

All-Purpose College Mentor with a Mechanical Specialty

Franklin W. Olin College of Engineering, Class of 2008
  #6   Spotlight this post!  
Unread 08-29-2005, 01:48 PM
Sparks333's Avatar
Sparks333 Sparks333 is offline
Robotics Engineer
AKA: Dane B.
FRC #1425 (Wilsonville Robotics)
Team Role: Alumni
 
Join Date: Feb 2004
Rookie Year: 2003
Location: Wilsonville, Oregon
Posts: 184
Sparks333 is a glorious beacon of lightSparks333 is a glorious beacon of lightSparks333 is a glorious beacon of lightSparks333 is a glorious beacon of lightSparks333 is a glorious beacon of lightSparks333 is a glorious beacon of light
Send a message via AIM to Sparks333
Re: Robot Adaptive Suspension

The other thing you could try that would be easier is to simply put pneumatic outriggers that pop out when the robot starts to tip. That way, the drivetrain would not be affected, and it may simplify construction.
Just a thought.

Sparks
__________________
ICs do weird things when voltage is run out of spec.

I love to take things apart. The fact that they work better when I put them back together it just a bonus.

http://www.ravenblack.net/random/surreal.html
  #7   Spotlight this post!  
Unread 08-29-2005, 11:06 PM
John Gutmann John Gutmann is offline
I'm right here
AKA: sparksandtabs
FRC #0340 (GRR)
Team Role: Mechanical
 
Join Date: Feb 2005
Rookie Year: 2004
Location: rochester
Posts: 804
John Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant futureJohn Gutmann has a brilliant future
Send a message via AIM to John Gutmann Send a message via MSN to John Gutmann Send a message via Yahoo to John Gutmann
Re: Robot Adaptive Suspension

what if you used something like a solenoid with a spring on the inside then just apply a analog voltage, because then with no voltage it has full travel but then as you apply voltage it could compress the spring, the only problem would be that the eletromagnets would be hefty and need to be really powerful
  #8   Spotlight this post!  
Unread 08-30-2005, 12:02 AM
Sparks333's Avatar
Sparks333 Sparks333 is offline
Robotics Engineer
AKA: Dane B.
FRC #1425 (Wilsonville Robotics)
Team Role: Alumni
 
Join Date: Feb 2004
Rookie Year: 2003
Location: Wilsonville, Oregon
Posts: 184
Sparks333 is a glorious beacon of lightSparks333 is a glorious beacon of lightSparks333 is a glorious beacon of lightSparks333 is a glorious beacon of lightSparks333 is a glorious beacon of lightSparks333 is a glorious beacon of light
Send a message via AIM to Sparks333
Re: Robot Adaptive Suspension

Sparksandtabs,
If I read you correctly, it would be consuming power all the time it was in, which could knock out your battery pretty quick. Powerful solenoids take quite a bit of current.

Sparks
__________________
ICs do weird things when voltage is run out of spec.

I love to take things apart. The fact that they work better when I put them back together it just a bonus.

http://www.ravenblack.net/random/surreal.html
  #9   Spotlight this post!  
Unread 08-30-2005, 06:00 AM
Don Wright's Avatar
Don Wright Don Wright is offline
Registered User
FRC #0469
Team Role: Engineer
 
Join Date: Jan 2003
Rookie Year: 2003
Location: Livonia, MI
Posts: 683
Don Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond reputeDon Wright has a reputation beyond repute
Send a message via MSN to Don Wright Send a message via Yahoo to Don Wright
Re: Robot Adaptive Suspension

Another idea would be to try something like what they use in tall buildings to stop sway from wind. Move a large mass in the direction opposite of the sway... Maybe like the battery.

Of course, the higher the battery is mounted on the robot, the more affect it will have, but also raise your CG, but it's just an idea...
__________________
Donald F. Wright Jr.
Product Manager
AVL Instrumentation & Test Systems, Inc.
  #10   Spotlight this post!  
Unread 08-30-2005, 07:19 AM
Gdeaver Gdeaver is offline
Registered User
FRC #1640
Team Role: Mentor
 
Join Date: Mar 2004
Rookie Year: 2001
Location: West Chester, Pa.
Posts: 1,459
Gdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond reputeGdeaver has a reputation beyond repute
Re: Robot Adaptive Suspension

Do first robots even need suspension? The game is played on a flat smooth field at low velocity. Now if First brings in a couple tons of rock and gravel for the playing field we need to talk suspension. For 2005 the basic problem was CG for many robots. Instead of spending time on active suspension, investigate arm designs that lower the CG. This can be done by keeping all the motors down in the frame and looking into materials that are lighter then metal. In 2004 and 2005 our team used composites for the arm and ball grabber. The weight saving were substantial. However, using composites takes different fabrication techniques than metal and need to be explored in the preseason. Composite and CG research would probably be much more productive.
  #11   Spotlight this post!  
Unread 08-30-2005, 07:38 AM
Jack Jones Jack Jones is offline
Retired
no team
 
Join Date: Jan 2003
Rookie Year: 2003
Location: Waterford, MI
Posts: 964
Jack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond reputeJack Jones has a reputation beyond repute
Re: Robot Adaptive Suspension

On the one hand, I wouldn’t want to discourage innovation. But on the other, I would want to encourage simplicity. I’ve seen absolutely no need for active suspension in any of the games so far. Why fight Mother Nature when you use her own rules against her? Keep your CG low. Put it in the center of your wheelbase. Allow the wheels to slip against lateral forces. Build in just enough resistance to eat momentum. Redirect the torque to where it helps instead of hurts. Use passive systems! If all that fails, then have a go active cancellation.

Just because you can do something, it doesn’t mean you should. That principal is so often ignored it’s not even funny, which it would be were the consequences not so fatal.
  #12   Spotlight this post!  
Unread 09-01-2005, 07:36 PM
Andrew Blair's Avatar
Andrew Blair Andrew Blair is offline
SAE Formula is FIRST with Gasoline.
FRC #0306 (CRT)
Team Role: Alumni
 
Join Date: Feb 2005
Rookie Year: 2004
Location: Corry
Posts: 1,193
Andrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond reputeAndrew Blair has a reputation beyond repute
Send a message via AIM to Andrew Blair Send a message via Yahoo to Andrew Blair
Re: Robot Adaptive Suspension

Thanks guys, I unfortunately leaped before I looked, and I didn't even think about the 60 psi cap, which would limit the capabilities as it was. Thanks again! I'll just have to work on my other out of the realm ideas!
__________________
Reading makes a full man, conference a ready man, and writing an exact man.
-Sir Francis Bacon

"Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction."
-Albert Einstein
  #13   Spotlight this post!  
Unread 09-09-2005, 10:56 AM
Alex.Norton's Avatar
Alex.Norton Alex.Norton is offline
Fidgetting
no team
 
Join Date: Apr 2005
Rookie Year: 2003
Location: Ft. Collins, Colorado
Posts: 190
Alex.Norton has much to be proud ofAlex.Norton has much to be proud ofAlex.Norton has much to be proud ofAlex.Norton has much to be proud ofAlex.Norton has much to be proud ofAlex.Norton has much to be proud ofAlex.Norton has much to be proud ofAlex.Norton has much to be proud of
Send a message via AIM to Alex.Norton Send a message via MSN to Alex.Norton
Re: Robot Adaptive Suspension

Quote:
Originally Posted by Gdeaver
Do first robots even need suspension? The game is played on a flat smooth field at low velocity.
whether or not a robot needs a suspension really depends on the drive system. If all of the wheels of a robot need to be in contact with about the same amount of traction, a suspension can mean the difference between being almost uncontrollable robot and one of the easiest robots to drive. At least this is what we found when we implemented an omni drive train this last year. theoretically an active suspension might help this but I doubt that the advantage gained from this would actually be worth the effort or the weight gain.

Alex
  #14   Spotlight this post!  
Unread 09-09-2005, 11:02 AM
Tytus Gerrish's Avatar
Tytus Gerrish Tytus Gerrish is offline
IGAB, ADHD, and Dislexic
AKA: Ty
FRC #0179 (SwampThing)
Team Role: Tactician
 
Join Date: Feb 2003
Rookie Year: 2001
Location: West Palm Beach, Florida
Posts: 2,018
Tytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond repute
Re: Robot Adaptive Suspension

i have play'ed arround with the idea of an active suspention on a robot, it's kinda cool and it makes sense that it would help, but the ammount of extra weight, time, and money killed the idea of putting it on a competition robot. also even though it does help, It dosen't help that much. the best thing that can be done is get your robot's cg So low what 8 pounds 10 feet in the air won't realy matter much.
Closed Thread


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
VCU NASA Regional Collmandoman Regional Competitions 83 03-10-2005 12:20 PM
2005 FRC Team Update 14 Jeffrafa General Forum 43 03-01-2005 02:52 PM
Manual placement of tetras Petey Rules/Strategy 7 02-22-2005 05:04 PM
Kamikaze Robot Strategy... Joe Johnson Rules/Strategy 30 04-07-2002 08:42 PM
Calling all Lawyers... ...Define "all parts" Joe Johnson General Forum 10 03-13-2002 02:12 PM


All times are GMT -5. The time now is 11:15 PM.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi