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.

[Skedaddle]

So if very little distance reqd between ball and radar for path measurement and average Joe ball speed of 135-145 will only need about 14 feet max for FS operation. They should change their marketing!

[sorensen]

So if very little distance reqd between ball and radar for path measurement and average Joe ball speed of 135-145 will only need about 14 feet max for FS operation. They should change their marketing!

which marketing :-) they have all worked in the CIA before, not much information to read

[Brutaly]

I asked a client of mine to do some testing today and i figured i should post some results. Its not scientific but its at least a hint.

One thing that i would like to add is that if you check the drivers numbers it seems he started to pull with his driver in the last series and he did. We did this test in under an hour and hitting 60 golfballs took its toll. You can find that the horizontal launch also changed rather massively, he got tired.

This is the order we did the test. We did 3 series.

1. Correct setup (green in summary pic)
2. 2 metres to the ball, correct distance to the screen. Minimum in the app is 229 cm (yellow in summary pic)
3. 2m to ball and 3m to screen. (red in summary pic)

Before each series with did a correct ball origin test and radar sight calibration.

Each series is 10 i9 shots and 10 driver shots.

In all series we had issues with getting correct spinn numbers but no set up was any worse than the other. It is most obvious in the i9 series. They changed light bulbs in my studio a day ago and i suspect they used some low energy stuff that messes with my radar. I need to check that out so take the spinn with a grain of salt.

The player is a scratch player which relies heavily on his short irons which is close to tour class.

He has rather low swing speed, about 95 mph with the driver. and averages about 220 (200m) yards carry.

What do you say, would you play simulation golf with these numbers? Would you play with all setups if forced to?

Having the radar closer than 2m from the ball isnt realistic, with a correct take away and a driver you need that space behind you.

[Bubba22]

Not sure what to make of this. The numbers are not perfect but then again neither ius the setup. Ideally you want three units measuring at the aame time or an Iron Byron that hits the identical shot eahc time in the different FS positions. Interestinb his driver spin is quite high in the correct setup!

[Brutaly]

Yeah the lights was a miscalculation.

I had no second LM as i did before so this is what i can accomplish atm, a very consistent sving. Better than 99,9% of the player base.

I actually find the numbers to be rather nice. Compare i9 series 1 and 2 and lateral differs approx 3,5m. 1,75m can be directly related to horizontal launch (1 degree) which leaves 1,75m due to different shot shapes (spin axis).

In my mind series 1 and 2 shows that at least that with i9 there is no issues using 2m as radar to ball and 4m to screen. I also think that series 3 with i9 is very much alright for simulation.

The driver is easy to explain. I told him to bring a i9 and his driver but he is a bit absent minded so he brought his i9 and a back up shaft that he wanted me altere.

He actually hit those drives with a 13 degree driver with a super lite regular shaft, way to soft and with the wrong bend profile so there is a lot messed up there.

[Bubba22]

Were these done with a ball with a mettalic dot?

[Brutaly]

Yes, all shots were made with the sticker ofc.

[Clubfitter73]

Not sure what to make of this. The numbers are not perfect but then again neither ius the setup. Ideally you want three units measuring at the aame time or an Iron Byron that hits the identical shot eahc time in the different FS positions. Interestinb his driver spin is quite high in the correct setup!

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.

What will suffer is mainly angle of attack, clubspeed and ofc acceleration-/speedgraphs.

If Aoa is not correct, clubpath is not correct.

Now i got a clarification on club path as well. Its not affected by distance from radar to ball.

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

[Clubfitter73]

Thought gear effect was not taken into account indoors, bit of a drawback for FS/TM against say GC2 HMT and obviously always assuming centre strikes

Yes, that's right. No gear effect indoors.

Can someone here explain to me what this means? What do people mean when they make these remarks, I really do not understand.......

[goatbarn]

It means the the spin axis is not measured indoors. And therefore the effects of "gear" during impact are not simulated in the ball flight/spin axis.

Indoors, FS determines spin axis from measured club path, AOA, and ball azimuth. Outdoors it's totally different.

So if you have an extreme toe hit, the shift of spin axis to the left (right handed example) is not captured.

Hence, no gear effect indoors.

[Clubfitter73]

It means the the spin axis is not measured indoors. And therefore the effects of "gear" during impact are not simulated in the ball flight/spin axis.

Indoors, FS determines spin axis from measured club path, AOA, and ball azimuth. Outdoors it's totally different.

Still have trouble understanding. spin axis can (imho) not be calculated from only club path, aoa and azimuth?
I miss face angle and ball flight curvation.

[goatbarn]

Face angle is not measure by doppler radar, it is calculated.

Obviously indoors, there is not ball flight curve.

So those 2 can't be used, hope you see that.

[goatbarn]

And saying spin axis is calculated is misleading. It's derived or estimated, as it's not an exact science.

[Clubfitter73]

Obviously indoors, there is not ball flight curve.

Let's assume a few things:
a) ball flight 4 meters (400cm)
b) Assume that the rule of thumb of 0.7% deviation for each 1 degree spin axis tilt is correct (quote from TM)
c) Assume that the initial azimuth angle resolution is 0.2 degree (quote from TM)
d) Assume that the spin axis tilt is 6degrees for a 0.14 inch (~1 dimple) misshit (driver) is correct (quote TM)

We then get the following equations
(1) 0,7% for each degree -> 6 x 0.7 = 4.2% flight curvation
(2) 400cm x 4.2% = 16.8cm side displacement due to curvation
(3) arcsin(16.8/400) = 2.4degree deviation from the inital azimuth.

That 2.4 degree is larger then the 0.2 measurement resolution so not only is there ball flight curvation indoor but the angle in relation with the initial azimuth is rather large even with only a 1 dimple misshit.

[goatbarn]

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