thank you for the reply.
Yes, it does look like a PIR sensor but it should be a microwave motion sensor based on the spec.
As i know (from the interent), there are types of motion sensor for home
1) Using PIR
2) Using microwave pulses
3) Using both
http://www.safewise.com/resources/motion-sensor-guidebut i not really sure if it is suitable or not.
We already the make the robot hit the ball when it static by using lots of IR sensors. Somehow the IR sensor really hard to detect fast small ball. (we are using ping pong size ball). It can hit only when we throw it slowly.
Range finder laser sensor and LIDAR sensor are too expensive =='
To find alternative, I think motion sensor is ok. But after reading the reply i think not suitable.
Maybe you guys can suggest any alternative sensor that can detect small, fast object. we are still working on kinect.(got no experience on kinect so it takes times to develop) so meanwhile we are working on it, we are trying to find other alternative.
Tqvm.