Hi @Hui , a good paper for an overview of how grid cells can be modeled, including their path integration properties, is A Hybrid Oscillatory Interference/Continuous Attractor Network Model of Grid Cell Firing
However, is your question specifically about how cells might read out the vector that the animal needs to travel in, in order to return to a particular location given a current location (i.e. path planning) using grid cells?
I’m not sure about a good paper on this read-out using grid cells - I’m sure they must exist, but you might find this talk by Barbara Webb that @weiglt shared a while ago interesting. She discusses how insects determine the homing path that they need to take to return to their nest - while not using grid cells, it’s still an interesting insight into how this kind of read-out might work mechanistically.
If you do find a good paper in your research, please feel free to share on here, as I would also be interested to take a look.