A friend of mine asked me to help with thinking about a solution to create a RF communication between 8 robots and 1 access point. Not a lot of traffic, just to signal that the robot is (almost) at the end of his track and get some control information. once per few minutes. This is not very complicated and I was thinking about the nRF24L01+ chip with external antenna. We need a range of approx. 100 - 150 meter. LOS
the complex part is the following:
it is used in a field with solar panels, and we need about 4000 robots and 4000/8 = 500 access points.
The addresses of all the units needs to be unique but each access point needs to know the addresses of his own robots. (and these robots has to know the address of their access point)
I was thinking about a silicon ID (32bit) and use a kind of pairing during start-up. So all the units have address 0 during start-up, and after pressing a button on the Tx, he will send a message with his unique ID. The Rx will store that ID into EEPROM or SRAM. The Rx will answer a message with his own address and the Tx will store that one into his SRAM.
the cons. are that you'll have to "pair" 4000 units....
the pros. are that you have 500 "independent" networks.
Anybody can give me other/better solutions? Or some suggestions to my current idea?
A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. The picture below illustrates how wireless mesh networks can self form and self heal. It is supported by Arduino Yun.
Yes, but that is too expensive. And not necessary.
is a robot
is robot track
AP = accesspoint
| * - - - - - - - -
| - * - - - - - - -
| - - * - - - - - -
| - - - * - - - - -
AP1 < 200m > AP2
| - - - - - - * - -
| - - - - - * - - -
| - - - - * - - - -
| - - - - - - - - *
So when using a rf tranceiver with a range of 150m LOS, it should be feasible I think. In worst case, an access point can receive 24 different nodes including "his own" 8 nodes.
Hi,
Just to get it clear, by track you mean solar tracker, fixed to the ground but tracks the sun.
Robots infers most of the time a travelling machine.
So, if I have it right, you need RF comms between 8 solar trackers and a node.
You have 4000/8= 500 nodes.
I assume you have another mode of connection between the nodes to communicate with the solar trackers?
The nRF24L01+ chip would fit the bill I'd say, I have a handful of them but family commitments have kept me away from playing with them.
TomGeorge:
Hi,
Just to get it clear, by track you mean solar tracker, fixed to the ground but tracks the sun.
No, the solar panels are fixed. And some cleaning robots are driving on a track. A kind of railway.
TomGeorge:
So, if I have it right, you need RF comms between 8 solar trackers and a node.
You have 4000/8= 500 nodes.
I assume you have another mode of connection between the nodes to communicate with the solar trackers?
Self-forming/Self-organizing
New nodes joining the mesh network are transparently supported because meshing functions such as neighbours discovery and topology learning are implemented. Wireless routers rapidly detect the presence of new paths, thus enhancing the overall performance and coverage
Self-healing
A node may leave a mesh network due to unexpected circumstances such as failure in the networking devices, natural disaster/man made disaster and such.Therefore ,the mesh network are inherently designed to be more robust and resilient. There are many ways to do this such as make it a multi-path for packets to travel from one nodes to another (the amount of connections between 2 nodes is 2 or more) , decentralized connections and redundancy.
Self Optimization
The mesh network have the self optimization to enlarge the mesh coverage as large as possible, to minimizes the interferences and also to maximizes the bandwidth capacity of the mesh network.
Multi-hop
Multi-hop connectivity allows several devices to access the network at once by relying on other mesh nodes without affecting the overall network performance. It will guarantees larger coverage zones and an enhancement of the network capacity. In fact, line-of-sight constraint no longer matters because the intermediate nodes relay the information to their neighbors on short wireless links using a reduced power transmission.
Okay, Mesh seems to be the better option as I read.
But there is only 1 AP an 8 robots per grid. So the grid 2 next to grid 1, has also a AP and robots and these are fully independent on AP1.
So AP1 should not do anything with data from grid 2. Also the APs do not communicate with each other.
For that reason, I would like to have a LOS range coverage of 150 meter, so we do not have too many interference on other APs.
