[robocup-small] [rc-ssl-tc] Chip kick interception challenge

[Alexander Danzer]

Hi, 

I like this proposal, especially as the random component from my
proposal may be less fair. 

The kick positions sound good, I had similar ones in mind. I would not
consider the third kick as the easiest however, 

as the ball might go out of camera sight at a certain height. 

With 4 participating teams, we have 48 kicks which would be reasonable
to do in 90 minutes. 

Just to be clear, the robot does not change the direction significantly
before the kick so that the intercepting robot 

has a chance to choose a reasonable starting position. 

Best, 

Alex 

On 2017-07-24 19:41, Andre Ryll wrote:

> I recommend to use three different positions for the chip kick. As I have implemented our chip kick detection I am well aware of the difficulties of detecting such kicks. I suggest the following positions:
> - From a corner to the center of the field. This is most difficult to detect as the ball goes through the camera axis and does not show a parabola in the images.
> - From a corner along the long side of the field. Here, a single camera is available as well but the ball shows a significant parabola. The ball may vanish from the images at its high points.
> - From the center to the goal or vice versa. This is most simple as the ball is visible on multiple cameras, basically providing you stereo vision.
> 
> We used these exact position at IranOpen. Furthermore, we used distances from 2 - 3.5m. Basically, we had 2m, 2.5m, 3m, and 3.5m in the bucket. Then we drew them in random order. Thereby, each team gets the same chips, but cannot predict the order they were executed. To speed up the challenge, this can certainly be reduced to two distances. The technical difficulties of the different positions might be used to weight scores. 
> 
> Cheers,
> 
> Andre Ryll
> Project Leader & Founder of
> TIGERs Mannheim
> 
> Am 24.07.2017 um 19:26 schrieb Danny Zhu: 
> 
>> That sounds reasonable to me, though I think we'll need to see it in practice. If the range needs to be wider, we can always add variation in the commanded distance as well. The exact distribution within the range shouldn't matter much, as long as the same thing is done for all competitors, right? 
>> 
>> Danny 
>> 
>> On 07/24/2017 07:18 PM, Alexander Danzer wrote: 
>>> That's a good point. 
>>> 
>>> However, when I investigated the possibilities of chip kick estimation, 
>>> I found that only considering a robot's orientation does not provide enough 
>>> precision for determining the kick's direction precise enough 
>>> for a distance of more than 3 meters. 
>>> 
>>> But we certainly should have some variety in the distance. When I wrote 
>>> 3.5 meters, I had in mind that the kick was performed with an ER-Force 
>>> robot, which has significant variations in the actual kick distance. 
>>> I would estimate deviations of around 20 centimeters for said distance, 
>>> but I have to check our current hardware tomorrow. 
>>> 
>>> So, what do you think of a distance in the range of 3.0 to 3.5 meters? 
>>> (with an ER-Force robot, this is quite hard to guarantee however with 
>>> an equal probability distribution). 
>>> 
>>> 
>>> On 2017-07-24 18:55, Joydeep Biswas wrote: 
>>>>> On Jul 24, 2017, at 6:22 PM, Alexander Danzer <alex at dnzr.name> wrote: 
>>>>> 
>>>>> The ball touches ground after 3.5 meters in field plane. 
>>>> 
>>>> If the chip kick distance is fixed, then the intercepting robot only 
>>>> needs to know the kicking robots orientation when the ball is kicked - 
>>>> it does not really need to do chip kick estimation. 
>>>> 
>>>> -Joydeep 
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