Problem with proximity sensor times

It was discussed how to deal with the measurement times of the proximity sensors.
The sensors send an ultrasonic pulse when triggered and write a digital 1 to the echo pin until the pulse has come back.
Assuming an obstacle is in 3.4m distance, the sonic has to travel 6.8m before it comes back to the sensor. Sonic speed is about 340m/s which equals a time of 20ms. With 10 sensors the maximum measurement time will could even be more than 200ms, which is definitely too much for waiting in a single tick. The balancing needs much faster ticks.
An alternative could be to check every tick for a return of the pulse, not wait explicitly for it without doing anything else. This brings another problem, because even with a maximum tick length of 1ms, the sonic can travel about 34cm in that time and it is possible to get inaccuracies of +/- this distance.
It seems to be the only possible solution to use a separate small microcontroller for checking the distances in all directions and providing the data to the main Arduino.
Later an Arduino Mini was bought, more details about different approaches coming...

Meeting 2015-05-28 16:00 - 17:00