Dear Eitan,

I did some more tests trying to reproduce the behaviour of driving
backwards. I failed.

The time I increased the rate of the /scan topic to 6Hz everything
worked well. Now I lowered the rate to 3Hz to test, if this was the
reason for the weird behaviour I saw 2 weeks ago. Even with this low
scan rate and lots of CostMap timeouts the planner works well.

I modified a couple of things in the meantime. The local planner
parameters are now very similar to the default values. I updated the
navigation stack to 1.0.7.

I am glad its working but I would also like to know why it was not
working right from the start. The only reason I can think of after I did
these tests today is that

1) there was a bug in the navigation stack I used 2 weeks ago and this
bug has been fixed
2) the local planner parameters I posted here lead to the poor
performance (I had very low acceleration values)

Regards
Christian