The transportation-power of the logistic bots is nearly constant! It depends on
- Speed of the bots
- Cargo-stacksize (number of items they can take at once)
- Number of bots
- Average distance between your chests (all combinations)
- How often they fly empty (the more "random" the transport is the better, because then there is a bigger chance that an empty robot is near!)
- How long they need to wait for recharge - this effect is "blocking", which means that up to an unknown maximum, the transport-power is constant. But, if the waiting queue gets too long, the system falls apart, which means that, counter-intuitively, a slightly lower number of bots is actually more efficient/faster!
To optimize it, one can
- Research speed or cargo-stacksize.
- Add more bots to your network
- Add more roboports at strategic points
- This is an expensive enhancement and sometimes doesn't help, but can solve the problem
- Decrease the average distance between the logistic chests
- avoid transporting a lot of raw material - instead use transport belts for items with a lot of throughput. Bring the big material flows as near to the target as possible. The transport-power of logistic bots is much bigger than belts, but a constant flow reduces their effectiveness by about half, because they fly empty about half the time.
- Split a big network in two and move items between them with transport belts or trains (and requester/provider-chests).
It's a very good idea to use a robotic network at a train station to unload the chests that have been filled by the inserters from the wagons. The logistic bots have enough time to recharge between trains. But don't also use them to transport the ore to the furnaces. For that the belts are much more useful, because the furnaces have a constant need for raw material and for constant flow belts are much more useful. This shows the flow:
Wagon ---Inserter---> Provider chest ---Logistic bot---> Storage- or Requester-chest Requester-Chest ---Inserter---> Belt ---> to the furnaces
Choosing the post for charging
Normally a robot flies to the nearest roboport to recharge. If the queue on that roboport is too long, they eventually choose another port. This is specified by the ratio of <distance to different roboport in tiles> / <queue size of robots waiting>.
Currently, to choose the more distant roboport, the distance must be at most <Number of robots in the queue and on the way> / 2.
So, to choose a roboport that is 10 tiles more distant, it has to have 20 less robots waiting in the queue.