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 .
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.
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… :ahh:
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.
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.
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
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
anon96464947,
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
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…
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.
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.
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! 
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
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.