Howto BF-PHYSICS-001: Transfer Functions

Ver. 1.0.5 (2023-02-04)

This module provides an example of using the transfer function method in MLPro for both default and custom implementation.

You will learn:

1. How to use the default type of transfer function (linear function)

2. How to set up your own function

Prereauistes

Please install following packages to run this how to

• Matplotlib

Executable code

## -------------------------------------------------------------------------------------------------
## -- Project : MLPro - A Synoptic Framework for Standardized Machine Learning Tasks
## -- Package : mlpro.bf.examples
## -- Module  : howto_bf_physics_001_set_up_transfer_functions.py
## -------------------------------------------------------------------------------------------------
## -- History :
## -- yyyy-mm-dd  Ver.      Auth.    Description
## -- 2022-08-24  0.0.0     SY/ML    Creation
## -- 2022-11-22  0.0.1     SY       Shift from mlpro repo to mlpro-mpps repo
## -- 2022-11-22  1.0.0     SY/ML    Release of first version
## -- 2023-01-14  1.0.1     SY       Shift from mlpro-at_basis.bf to mlpro.bf
## -- 2023-01-15  1.0.2     SY       Package renaming
## -- 2023-01-16  1.0.3     SY       Update due to __call__
## -- 2023-01-24  1.0.4     SY       Quality Assurance on TransferFunction
## -- 2023-02-04  1.0.5     SY       Shift UnitConverter from bf.systems to bf.physics
## -------------------------------------------------------------------------------------------------


"""
Ver. 1.0.5 (2023-02-04)

This module provides an example of using the transfer function method in MLPro for both default and
custom implementation.

You will learn:

1) How to use the default type of transfer function (linear function)
    
2) How to set up your own function

"""


from mlpro.bf.math import *
from mlpro.bf.physics import *
import math



if __name__ == "__main__":
    p_print = True
    p_visualize = True
else:
    p_print = False
    p_visualize = False
    
    
# 1. Using default type

# 1.1. Initialize a given default transfer function
myTF_linear = TransferFunction(p_name='Linear_TF',
                               p_type=TransferFunction.C_TRF_FUNC_LINEAR,
                               p_dt=0.01,
                               m=5,
                               b=2)


# 1.2. Call the defined transfer function
# 1.2.1. For a specific point
p_input = 10
output = myTF_linear(p_input)
if p_print:
    print(output)

# 1.2.2. Within a specific range
p_range = 5
output = myTF_linear(p_input, p_range)
if p_print:
    print(output)
    
# 1.3. Plot the graph
if p_visualize:
    myTF_linear.plot(p_input, p_input+p_range)


# 2. Using own function

# 2.1. Set up your custom function class
class MyTransferFunction(TransferFunction):
    
    # 2.1.1. Set up which parameters required for your transfer function
    def _set_function_parameters(self, p_args) -> bool:
        """
        y(t) = A cos(w * t - phi)
        """
        if self.get_type() == self.C_TRF_FUNC_CUSTOM:
            try:
                self.A = p_args['A']
                self.w = p_args['w']
                self.phi = p_args['phi']
            except:
                raise NotImplementedError('One/More parameters for this function is missing.')           
        return True
    
    # 2.1.2. Set up the mathematical calculation of your transfer function
    def _custom_function(self, p_input, p_range=None):
        """
        y(t) = A cos(w * t - phi)
        """
        if p_range is None:
            return self.A * math.cos(self.w * p_input - self.phi)
        else:
            points = int(p_range/self.dt)
            output = 0
            for x in range(points+1):
                current_input = p_input + x * self.dt
                output += self.A * math.cos(self.w * current_input - self.phi)
            return output
            
# 2.2. Initialize the transfer function
myFunction = MyTransferFunction(p_name='DGL_solution',
                                p_type=TransferFunction.C_TRF_FUNC_CUSTOM,
                                p_dt=0.05,
                                A = 3.5,         # Current
                                w = 314.15,      # angular velocity
                                phi = -120)      # angle offset


# 2.3. Call the defined transfer function
# 2.3.1. For a specific point
p_input = 0
output = myFunction(p_input)
if p_print:
    print(output)

# 2.3.2. Within a specific range
p_range = 10
output = myFunction(p_input, p_range)
if p_print:
    print(output)

# 2.4. Plot the graph
if p_visualize:
    myFunction.plot(p_input, p_input+p_range)

Results

Cross Reference

• API Reference: Physics