Finding the Density of a Ball

VEX V5 General Discussion General Forum
1

With the issue of the “squishiness” of a ball being a problem for some I would like find out how teams could integrate the ability to find the ball’s density before shooting it into the net. Having the ability of finding the ball’s density while onboard the robot would allow the robot to know how to change the speed in order to make the ball reach the net. Mass (M) divided by volume (V) = Density (P). Knowing this we can figure out the density of the ball. We are given ,in the manual ,a little information about the balls.

The mass may differ because the problem that was caused when the balls were made. So what I am trying to figure out is how we can measure the mass of the ball on the robot. Is there a way to do this using a sensor in a different way than it is usually used? Our team is currently doing reattach on PID controllers and trying to figure out how to do that, but we have a competition in 3 weeks and we are not sure if we will figure that out in time.

Our team needs a backup-plan and we think this would be the best thing to do right now. Being a full court and half court shooter we need to be able to tel the density of the ball while on he robot so that it can automatically decide the necessary speed of the flywheel while in middle court or half court. If someone could please provide some info on how to discover the mass while the ball is in the conveyor system that would be great, but until then every time a ball fire it can very in the trajectory although the speed of the flywheel is the same.

2

I’m not sure how it can be done with the field balls, but the preloads can be weighed before the match starts and sorted accordingly.

3

I don’t think it would be possible to make an accurate weighing mechanism with VEX parts and sensors that works quickly enough. I’m sure it is possible to make some sort of balance using potentiometers and a movable weight, but it would probably slow down the shooting process a lot, to the point where it would be more efficient to miss a couple of shots.

Also, from what I’ve noticed, the weight of the ball has very little to do with the firmness of the ball. I’ve seen balls that weigh the same have different squishiness, and while usually the lighter balls are softer this doesn’t always apply, for example I’ve seen a ball that is almost 60grams be really squishy.