Week 13

Final evaluations approaching :) …. Hello everyone, hope this blog finds you well.

From now I have 2 weeks remaining in Google Summer Of Code’23. Implementation of the State Space Model is finished. This week I focused on how operators interact with the State Space class.

Aim :

This week I made some comments towards the State Space model. It can be viewed here. I also opened up an issue - Planner on future implementations in the State Space Class.

Work : Let us go through the Pull Requests in brief.

1. Addition and Multiplication :

   >>> from sympy import Matrix
   >>> from sympy.physics.control import StateSpace
   >>> A1 = Matrix([[1]])
   >>> B1 = Matrix([[2]])
   >>> C1 = Matrix([[-1]])
   >>> D1 = Matrix([[-2]])
   >>> A2 = Matrix([[-1]])
   >>> B2 = Matrix([[-2]])
   >>> C2 = Matrix([[1]])
   >>> D2 = Matrix([[2]])
   >>> ss1 = StateSpace(A1, B1, C1, D1)
   >>> ss2 = StateSpace(A2, B2, C2, D2)
   >>> ss1 + ss2
   StateSpace(Matrix([
   [1,  0],
   [0, -1]]), Matrix([
   [ 2],
   [-2]]), Matrix([[-1, 1]]), Matrix([[0]]))
      
   >>> A = Matrix([[-5, -1], [3, -1]])
   >>> B = Matrix([2, 5])
   >>> C = Matrix([[1, 2]])
   >>> D = Matrix([0])
   >>> ss = StateSpace(A, B, C, D)
   >>> ss*5
   StateSpace(Matrix([
   [-5, -1],
   [ 3, -1]]), Matrix([
   [2],
   [5]]), Matrix([[5, 10]]), Matrix([[0]]))
   

2. Future Implementations in the State Space Class :

   Make the class more feature rich -

   • Solve examples mentioned in issue and add them to the control_problems file . The required functionality is already supported in the pull request.
   • Add a symbolic solver (and a numeric solver if required) with the help of the ODE module to solve x' = Ax + Bu form.
   • Read about Laub’s or Horner’s method to evaluate system transfer function at complex frequency. This will be the equivalent of eval_frequency for Transfer Functions.
   • Add Feedback interconnection between 2 state space LTI systems.
   • Other features can be picked up on comparison with MATLAB and python-control.

   Extension of the class (long term)

   • Allow the argument dt to create a discrete time model following the completion of continuous time model. It will be nice if we could support this for both Transfer Function model and State Space model.

Future Work : Now, the pull request and issues are completed from my end. I am waiting for the maintainers to suggest suitable improvements so that it can be merged soon.
The next week I will have my minor exams at university so I won’t be able to do too much work.
Following week will be my last official active week for Google Summer Of Code. It has been an amazing journey with a few final touches remaining.