# Tuned mass dampener

So our team is foreseeing some problems with swing when traversing to highbar and then to traversal. You think a Tuned mass dampener like a pendulum or sliding block would even be worth the space and weight to have to help make the decay faster on the swing.

Ya know, if you just slide the batteryâ€¦

Iâ€™d link the JVN blog gif someone is bound to bring up but it seems that those are all broken/gone now.

7 Likes

If it can stop the windows from popping out of a skyscraperâ€¦

1 Like

thats what i was thinking the main concern is how much weight its going to take up

To make it work, you would need to be able to shift a significant percentage of the total weight of your robot. So you either need to build under your total weight budget so you can add ballast later, or you need to make use of the mass already present on your 'bot. As Troy suggests - slide the battery.

Whether this is feasible, safe, and can be built within the game rules is left as an exercise for the reader.

Gone? Nope. Now if I knew which one you were after Iâ€™d go straight there.

1 Like

Dang, this forum reads minds. I was thinking about tuned mass damping and here it is.
Really though what might work even better is ACTIVE damping - a weight that can be shoved around to counteract the swing, on a belt or driven arm. The programming is non-trivial and would require a gyro, but I bet someone tries it

1 Like

Perhaps instead of implementing a tuned mass damper you could increase friction on the rungs? Ultimately you want to transfer some of the potential energy (if not all, depending on how the climber would work) from the robot when moving between rungs. You could either change the material to increase the coefficient of friction or clamp onto the rung harder to increase the normal force.

2 Likes

The gifs have all disappeared. Well, replaced really

While weâ€™re here @scoopbot, check out 2481 2019. They actually implemented the sliding mass on an underweight robot to achieve a â€śfingertipâ€ť hab 3 climb. Looking for pics rn. forgot to take pics, was having too much fun memeing.

2 Likes

A tuned mass damper stores the kinetic energy and releases it at some other time, damping your motion. The energy never goes away so the question is â€śwhat will you do with the stored energy that is benignâ€ť. I suspect it would be very easy for this to go very wrong and start oscillating if the tuning is not done correctlyâ€¦

Some sort of friction damper that would dissipate energy might be a better solution.

4 Likes

IMO: This is a solution looking for a problem.

Your time is better spent on other aspects of the game and either:

2. dampen the swing with friction

These things did find themselves into the noses of F1 cars though. So I donâ€™t have tons of ground to stand on other than they have more minds, bigger budgets, and the game doesnâ€™t change every year.

17 Likes

I agree with several of the posters above - in this case, friction is your friend!

Added: you could also use your climb arm extension/retraction to dampen the swing, doing what people do to â€śpumpâ€ť a playground swing but in reverse. That is, drop near the end of the swing, and climb in the middle of the stroke.

The control logic and sensors needed to actively damp this swing is worth considering. But the mass associated with such a system is still going to be significant.

1 Like

I see what your saying and im tending to agree but i prototyped it with a swinging dumbbell in a swinging bot and it did do something i think part of the main problem is tuning it to the bot since the way the bot moves and the way the TMD moves have to be almost completely opposite.

Now that itâ€™s been several weeks, has anyone found particularly good materials to increase friction against the rung? We tried surgical tubing and some black wheel tread but it didnâ€™t seem to reduce the swing in our climb versus just aluminum (weâ€™re using the AndyMark Climber in a Box hooks).

Have you considered what they make pipe wrenches out of?

Scratch that, you you considered bolting pipe wrenches to your climber arms?

Can you provide a photo or link for the type of wrench you are referring to?

The pipe wrenches (monkey wrenches) I have are all steel and grip the pipes using ramp-shaped teeth on both jaws. It is possible that they would damage the powder coating applied to the rungs if they were gripping them and turned.

@scoopbot you can solve a problem by directly addressing the result of an issue (reducing the swinging) or you can address the root cause of the issue (ability to swing). Sometimes, the difference is not easy to discern.

I donâ€™t know why, but Iâ€™ve always fascinated with dampeners. Theyâ€™re just so cool and the physics is really neat. A skyscraper in my area has a gigantic water tank on top of it that functions as a dampener and it is super cool looking!

Not sure how well this would work without a full tight wrap but for 5 bucks it might be worth a look?