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 Post subject: Re: Robo Pong 2050
PostPosted: 22 Aug 2014, 07:57 
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hopper wrote:
Thanks Larry for your elaborate reply,

First of all, you have confirmed to me that the ball should bounce on the robot's side first (From Samson Dubina's Youtube videos of all drills, that didn't became clear to me).

Secondly, I did the test as you described below and, similar to drill #11, the ball did bounce on the robot's side first but only halfway the table and then didn't clear the net. Only, as you proposed, by means of increasing the head angle and increasing the Speed Calibration, I was able to reproduce a ball that cleared the net.

There could be another cause of the problem, based on my following observations.
1. The particular robot requires a pretty high Oscillation calibration, based on the Oscillation Test. I have to adjust it from 25 to 14.
2. With OSC CALIB on 14, the oscillation range seems a bit "skewed"; in Normal mode, I have to define L Position to 13 for receiving a ball on the centerline of the table, so position 20 has now improved (see item 3) but position 10 is left of the centerline.
3. In spite of the OSC calibration, balls placed to position 20 still seem to go pretty wide, having the first bounce nearby the side line and the second bounce off the table.

Therefore it might be that position 20, being a little more positioned to the sideline of the table then intented, is a large contributor to the problem. I will test this in Normal mode with a combination of speed 2, angle 8.5 and a position of 19,18,17 to check if/where the ball would cross the net.
Furthermore I might,on short term, check/correct the alignment of the servo drive pin in order to improve the oscillation calibration.

As for the motor drive pin cleaning, am I correct assuming the following sequence;
1. Disconnect robothead from pivot guide by unmounting screw 72 and 69 (figure E in manual)
2. Open up motor head by unmounting the 4 screws 71 (figure D in manual)
3. Disconnect Motor Wheel by unmounting screw 81 (figure C in manual)
4. Clean the drive pin
Or should I disconnect other items as well ?

I'll keep you informed of my findings,

Best regards,

Hopper, oscillation problems should be completely separate from ball speed problems. Resolve ball speed problems by adjusting BALL SPEED, limiting SPEED RANDOM, tweaking head angle, and as a last resort, SPEED CALIB. If those adjustments don't work, you almost certainly have worn parts that need replacement or you have that situation I described with filamentous material strangling your Ball Speed Motor.

Oscillation problems involve different parts and control box adjustments. Use OSC CALIB to set the landing spot of the 5 test balls so they land along the centerline of the table. A setting of 14 is not unusual--I've seen settings as low as 5. Once OSC CALIB has been set, all of the oscillator positions (0-20) should be correct with 0 throwing the ball off your left sideline, 10 throwing a ball down the centerline of the table, and 20 throwing the ball off the right sideline. If you don't want a ball to cross over the sideline, you will need to limit your position from 2 to 18--that oscillator range should roughly place the ball from BH corner to FH corner.

A caveat to the above is that low ball speeds, like the 2 setting you say you're using, may not allow the ball to cross a sideline when position is set at maximum [0 or 20], but much more speed than that will indeed result in the ball crossing the sideline. And an exception to this rule would be if you add sidespin that curves away from the sideline, in which case higher speeds can be used and the ball won't cross the sideline because the sidespin is altering the flight of the ball. You can see this effect on drills 17-20 that replicate sidespin/topspin and sidespin/backspin serves. Examine the settings for these drills in Robo-Soft and you will see that we had to intentionally limit the positions toward one side because the sidespin caused the ball to not land on the table when the widest position was used. One sidespin will cause a ball to curve towards the sideline and the opposite sidespin will cause it to curve away from the sideline. You'll need to compensate for this effect by not using the widest position settings to one side or the other, depending upon which sidespin is selected (left or right).

A similar effect is seen when choosing very high speeds and maximum positions. At max speed 30 and max right position 20, the ball probably will not land on the table regardless of the head angle setting. You'll need to either reduce the speed or have the ball land closer to the corner of the table instead of aiming for the sideline. You can see this on drill 64 where a full speed (30) loop is thrown to position 8 (a right-hander's typical switchpoint) followed by a medium speed (probably 23 or so) loop to position 20 (wide forehand) because a higher speed resulted in the ball not landing on the table due to the extreme angle.

If you're able to calibrate the oscillation at 14 and the balls are landing along the centerline of the table, I don't see that resetting the alignment of Oscillator Drive Pin on the servo will do any good. About the only time that helps is when you're at either extreme of the OSC CALIB range (0-50), and you're not at an extreme if you can calibrate at 14.

Regarding your head disassembly procedures, you can skip your step 1--it's unnecessary. Instead, before you start loosening any screws, take an Exacto knife or razor blade and split the Head Label and Spin Label down the seam that separates the left head housing from the right head housing. Also regarding Step 3, that screw has left-hand threads, so loosen by turning clockwise. You won't need to disassemble anything else, but we always recommend disassembling on top of a rag or towel to prevent parts from getting lost as the head comes apart.

Good luck.



 Post subject: Re: Robo Pong 2050
PostPosted: 26 Aug 2014, 16:43 
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Blade: Timo Boll ALC
FH: Donic Bluefire JP02
BH: Donic Bluefire JP02

The problem of the short ball in the net seems to be solved. :)

Based on your explanation of Speed Calibration, I reset this value to default 10.
As a result, drill #11 now started with a perfect short ball crossing the net.

I'm still not sure what did cause the problem last time, cause I started altering the speed calibration value from default 10 to 15 after the problem occured.
However it is solved and that is the most important thing. Furthermore I learned a lot about the construction of the robot and its maintenance procedures, which is also valuable information.

Thanks again for all your support.

All men can see these tactics whereby I conquer, but what none can see is the strategy out of which victory is evolved.
sun tzu

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