Hi,
I am new to robotics and was testing my skills on Palm Island. I am aware that we can check for obstacles, but in palm island scenario we get lake in from of us. I need correct sensor to identify. I dont find any sensor which can identify lake as an obstacle.

Generally, the paths developed into Palm Island avoid the water (and if your robot gets too close to the edge of the island, it may end up going for an unplanned swim ), and there isn't a sensor on the robots designed specifically to sense the water. However, you could possibly use the line tracker sensors to detect an edge, but it would be very, very tricky to do and I would not recommend relying on it (because of the angle of the robot when it approaches the water, the robot would have to be very close to the edge of the island before it could even detect a drop and at that point it may be too late).

Thanks John. Actually I want to avoid using wait1Msec function as it is some sort of hardcoding. But seems like there is no way to avoid water scenario using sensors.