Is it possible to access the study output variables in AnyBody at runtime.
For example, I want to access
which is an array of position vectors.
I want to retrieve the value of vector at previous time step and use it in the script for computation at current time step.
As far as I understand your problem, I am afraid there is no easy solution for this kind of problem at the moment. The reason is that you will get a kind of hen-egg problem when all the variables are created: since the output is not user defined, it will be generated during load time depending on the model and other variables in the study. Thus it is not possible to refer to objects that will be created at a later point.
As a workaround I could think of using a python hook function: With an AnyFunExMonoPy you can use a python function doing some calculations and operations with input from your model which can create also return values to the model. If this function is called every for every time step, you could save whatever values you have to a file and read these values in when you need them.
I hope this helps you with the problem. Otherwise please add a more detailed example of the problem.