Connect multiple RoboMasters to a single point - HU-ICT-LAB/RobotWars GitHub Wiki
Purpose of this article
Because we are going to use multiple RoboMasters for our project we also need to be able to control them via a central point, in this article you will find information about connecting via the network.
Connect multiple RoboMasters to one single point
We need to know how we can connect all of the RoboMasters to a single point. Since the robots can be controlled by 2.4ghz and 5ghz wifi frequencies the most viable option would be to just use any standard wifi router.
The first thing we have tried is connecting all of the RoboMasters to the schoollab network in our school building. It was working to some extent but the responsiveness of the RoboMasters was not great. The issues we've encountered were probably due to the network being quite busy with other students logged in on the network. The next option was to create our own network and connect everything to that. We have ordered this router recommended by the spec page and when we connected everything to this network it worked way better. For this project this router will do the job quite well.
If a RoboMaster is connected to a router instead of directly via wifi there will be a slight increase in latency. According to the RoboMasters' spec sheet the latency will be increased by 20-40 milliseconds which is negligible.
The router also allows us to give each RoboMaster a fixed ip, this way we can tell the router that RoboMaster 1 always has the ip 192.168.1.101 and RoboMaster 2 always has the ip 192.168.1.102 etcetera. This can be useful for identifying the RoboMasters.
This can be done in the router settings, DHCP → Address Reservation → Add New → Fill in the MAC address of the RoboMaster and the desired IP address.
How much bandwidth is going to be used?
According to the RoboMasters' specs the video bitrate is 6Mbps, this will be the biggest part of data per robomaster. If we want to send all video feeds of the three RoboMasters we only need 18Mbps. Since our router is capable of 1300Mbps on 2.4ghz and 1750Mbps on 5ghz we will have more than enough bandwidth left for all of the other data that needs to be transferred and for extra devices such as a laptop or mobile phone to control the RoboMasters.
Sources
RoboMaster S1 - Specifications - DJI. (n.d.). DJI Official. Retrieved November 5, 2021, from https://www.dji.com/robomaster-s1/specs