Distance from radar to ball in simulations

[Brutaly]

Just wanted to let you guys now that i had a long conversation with the head of sales in Europe regarding Xi and Xi+ earlier today and one thing that came up was distance from ball to radar in a simulation setting.

In a pure simulation setup the radar can stand as close as possible. What will suffer is mainly angle of attack, clubspeed and ofc acceleration-/speedgraphs. He said it will not affect how the radar reads the balldata after impact and all the data needed for a "perfect" simulation is measured after impact. So basically <5,5 meters for a perfect sim setup. So with a shallow swing a bit further and with a steep swing a tad closer. Just dont hit the radar.

[billydruce]

Assume the metal dots only help with total spin measurement then

[goatbarn]

Thats correct.

[Clubfitter73]

here's a quote from a trackman engineer:

4. Spinaxis

When indoors TrackMan determines the spinaxis from the short amount of ballflight combined with club data. This way of determining the spinaxis is very good except for off center impacts with woods (note that it is only off center impact in the heel-toe dimension which is an issue). The way TrackMan determines the spinaxis indoors does not take into account the gear-effect which affects spinaxis.
Example (right hand): Say, you hit it on the toe-side, then the spinaxis should be more negative (draw), but isn't indoors.

When outdoors, TrackMan determines the spinaxis from the measured aerodynamics which is quite accurate.

Regards,
Andreas Willadsen
Engineer
TrackMan A/S

That's an interresting remark made by this engineer. That would possible indicate that the radar is not able to see the curvation in the 4meter ball flight. Might mean that there is not enough data points in that ball fight lenght for the trackman. (Just thinking out-loud) would that also not mean that azimuth could be really wrong as well......Even more interresting is why that is only in the horizontal and not in the vertical ! Or (also very interresting part of the remark) why only with woods? A 1/2inch mishit with an iron 6 will also generate ~ 7 degree spin axis tilt......

mhhh ...funny...

[Brutaly]

Look at the smash factors. It's clear that there is an issue with the club head speed measurements. If the clubhead speed can not be determined then the impact is not found. If the impact is not found then all impact related data is also wrong.

If Aoa is not correct, clubpath is not correct.


Personally I think you getting these replies from a sales person and his only objective is .....to sell...

Why is there an issue with clubspeed/smash factors? They look very similar, imo, between the proper setup and the one with shorter distance between ball and radar.

I was unclear, AoA isnt messed up by radar distance explicitely. What messes it up is that the device gets very sensitive if the setup isnt 100% correct. 1 cm incorrect tee height has roughly 33% more impact on AoA with 2 meters to the radar compared to the proper 3 meters. The thread is about simulation and in such an environment you can actually set it up extremely precise, probably even more precise compared to when you set it up on the range for instance.

You are right, he is a sales rep but as i wrote he didnt answer my questions himself but checked them out with FS support.
And apparently he has such a good reputation, regarding his competence, that FS bought his company just to get him on board. I think that counts for something.

[mystic]

path is 100% affected by the distance from radar to ball because the path is related to the AOA, which is the most affected number when the radar isn't the right distance. Tee height also lets the radar know if the ball is sitting above the bottom of the radar, like when its on a mat. you also must ensure you choose DRIVER when hitting off a tee and an iron when off the deck. distance from radar to ball has an effect on the club data... distance from ball to wall has an effect on ball data. I hope this clears things up.

[Dax]

I'm not sure the comment that you need to let the radar know what club is being used is accurate. Can you elaborate? I would agree that having the radar the appropriate distance behind the ball is important and that there is a min distance for the ball to be.

[goatbarn]

It does have to know when you're hitting off a tee (Driver) when used indoors/outdoors. It tells the unit to look higher in order to get that important impact club data.

Now, the only thing they need for ballfight to be accurate is the spin axis number since the other ball data is directly measured (total spin, speed, launch, azimuth). So if you're ok with the spin axis accuracy when used indoors to suffer slightly, you can have less distance from radar to ball. Club data does suffer, but the only ball flight accuracy loss you'll see is the shape. I can't say it would measure a -10* axis as +10*, because there is no way to accurately test this.

When used off turf, the unit will see the ground interaction with the club and know where the ball was vertically, so you set the tee height to zero even if the ball is a few inches higher.

This is from maybe the only rep I trust from Flightscope.

[Dax]

Thanks I understand, so this is a requirement for using FS then in terms of letting the software know the balls position?

[Brutaly]

path is 100% affected by the distance from radar to ball because the path is related to the AOA, which is the most affected number when the radar isn't the right distance. Tee height also lets the radar know if the ball is sitting above the bottom of the radar, like when its on a mat. you also must ensure you choose DRIVER when hitting off a tee and an iron when off the deck. distance from radar to ball has an effect on the club data... distance from ball to wall has an effect on ball data. I hope this clears things up.

Nothing new and that isnt the issue at hand.

The question is HOW the measurement of path/AoA/etc is affected by a shorter distance.

Is it the distance itself that decreases accuracy or the relative less accurate setup the shorter distance brings that decreases accuracy or a third unknown alternative?

Goatbarn!
I got some info that tee height also affected AoA but you say that only has any impact when hitting the driver? The device dont have to be setup for specific tee height when hitting irons?

[goatbarn]

You always have to use the actual tee height when hitting off a mat, whether on a tee or not.

But you're supposed to set it up as 0" when hitting off turf.

So tee height to hitting surface always measure and input when indoors on mat, and tee height to hitting surface is set to zero when hitting outdoors.

This is what I've been told but as you see different reps have different stories.

[goatbarn]

This is because there is no divot or spray produced from hitting off a mat, and therefore the radar can't back-calculate the ball's vertical offset when indoors.

Enter tee height and it looks on that plane.

[Brutaly]

Thx, i misunderstood your post. I got the same explanation as you.

But as you say, there are different stories on allmost everything. Smoke screens and mirrors.

[Brutaly]

One interesting thing is that one of the more active members in the FB usergroup states that he done testing side by side with a gc2/hmt and got the exact same numbers with 9ft to the ball and 10ft to the screen. Aoa differed but also differed with the correct distances in the setup.

[leoapd]

Hey guys. New XI+ owner. Had it for about one week. So far it's been insightful the data it provides, just not happy with the accuracy so far. I am 8' sensor to ball and 13'5 mat to net. Lighting is fine, which is LED. I'm consistently 20+ yards short on all shots. Seems club data is really close as far as speed goes, but yardage is off. My mat sits 2.3" or so above ground level, but app only allows for full inch increments in settings. I have it set at 2. Could this be affecting my numbers that bad? Have not had it outdoors yet, but will try it soon. This is a mostly indoor unit. Thanks.

[Dax]

I'm not an Xi owner, but have you checked the following:

1. metal dot facing away from unit or at ceiling
2. What elevation and temp is your unit set at (I assume they allow you to set these parameters)
3. Can you raise the unit so that it is at the right height or at least to get rid of your .3 inch difference. I can't recall the appropriate way to set up the unit but you should ensure it is at the correct height in comparison to you mat. I would assume that the base of the monitor must be at the same height as your mat (I.e the feet are at the height of your mat). I'm sure someone here can comment on this point.