API Reference

pyadrc.pyadrc

Active Disturbance Rejection Control for Python

It is highly recommended to check the documentation first before attempting to use the package. Although it is simple in nature, ADRC requires some basic knowledge about PID control, observers and state-feedback.

class pyadrc.pyadrc.StateSpace(order, delta, b0, t_settle, k_eso, eso_init=False, r_lim=(None, None), m_lim=(None, None), half_gain=(False, False))

Discrete linear time-invariant state space implementation of ADRC

Parameters

orderint

first- or second-order ADRC

deltafloat

sampling time in seconds

b0float

gain parameter b0

t_settlefloat

settling time in seconds, determines closed-loop bandwidth

k_esofloat

observer bandwidth

eso_inittuple, optional

initial state for the extended state observer, by default False

r_limtuple, optional

rate limits for the control signal, by default (None, None)

m_limtuple, optional

magnitude limits for the control signal, by default (None, None)

half_gaintuple, optional

half gain tuning for controller/observer gains, by default (False, False)

__call__(y, u, r, zoh=False)

Returns value of the control signal depending on current measurements, previous control action, reference signal.

Parameters

yfloat

Current measurement y[k] of the process

ufloat

Previous control signal u[k-1]

rfloat

Current reference signal r[k]

zohbool, optional

Only update every delta seconds, by default False

Returns

float

Current control signal u[k]

property eso_states

Returns the states of the linear extended state observer

Returns

tuple

States of the linear extended state observer

property magnitude_limiter

Returns the magnitude limits of the controller

Returns

tuple

magnitude limits of the controller

property rate_limiter

Returns the rate limits of the controller

Returns

tuple

Rate limits of the controller

reset(x0=None)

Resets the extended state observer

Parameters

x0np.array, optional

new initial state vector for the extended state observer, by default None, i.e. resets to zero

class pyadrc.pyadrc.TransferFunction(order, delta, b0, w_cl, k_eso, eso_init=None, r_lim=(None, None), m_lim=(None, None), half_gain=(False, False), method='general_terms')

Discrete time linear active disturbance rejection control in transfer function representation

Parameters

orderint

first- or second-order ADRC TF

deltafloat

sampling time in seconds

b0float

modelling parameter b0

w_clfloat

desired closed-loop bandwidth

k_esofloat

observer bandwidth is parametrized as k_eso-multiple faster than w_cl

eso_initnp.array, optional

initial state for the extended state observer, by default None

r_limtuple, optional

rate limits for the control output, by default (None, None)

m_limtuple, optional

magnitude limits for the control output, by default (None, None)

half_gaintuple, optional

half gain tuning for controller/observer gains, by default (False, False)

methodstr, optional, ‘general_terms’ or ‘bandwidth’

method with which the transfer function parameters are calculated, functionally identical, but general_terms is used to implement half

gain tuning

__call__(y, r)

Control loop call

Parameters

yfloat

current output signal

rfloat

current reference signal

Returns

float

control signal to the plant (accumulator output)

property accumulator

Get accumulator

Returns

float

accumulator output

property parameters

Get parameters

Returns

dict

calculated paramaters

pyadrc.pyadrc.saturation(_limits, _val)

Saturation function

Parameters

_limitstuple

saturation limits (low, high)

_valfloat

sat(_val)

Returns

float

saturated signal

pyadrc.models

class pyadrc.models.QuadAltitude(dt=0.001, m=0.028, g=9.807)

Discrete-time model of altitude of a quadcopter

Parameters

dtfloat, optional

Discretization time (zero-order hold), by default 0.001

mfloat, optional

Mass of the quadcopter, by default 0.028

gfloat, optional

Gravitational acceleration, by default 9.807

__call__(u)

Input port to the quadcopter

Parameters

ufloat

Thrust of the rotors

Returns

float:

Current altitude of quadcopter

reset()

Reset position and velocity to zero

property states

Return the state of the quadcopter

class pyadrc.models.RandomSystem(states=1)

__call__(u)

Call self as a function.

class pyadrc.models.System(K=1.0, T=1.0, D=None, delta=0.001)

Python class to generate a first-or second-order process for simulation and verification purposes

Parameters

Kfloat, optional

system gain, by default 1.0

Tfloat, optional

time constant, by default 1.0

Dfloat, optional

damping factor, by default None

deltafloat, optional

discretization time in seconds, by default 0.001

__call__(u)

System response w.r.t. control signal u

Parameters

ufloat

control signal u

Returns

float

system response y