brian.motors.motor_types package

Module contents

class brian.motors.motor_types.DeviceClass(*values)

Bases: Enum

NONE = 0

ERROR = 1

EV3_ANALOG_MOTOR = 2

EV3_UART_DEVICE = 3

class brian.motors.motor_types.DeviceType(*values)

Bases: Enum

UNKNOWN = 0

NXT_EV3_LARGE_MOTOR = 7

EV3_MEDIUM_MOTOR = 8

class brian.motors.motor_types.MotorType

Bases: object

property name: str

Human-readable name of the motor

Type:

return

property identification: Identification

What will Brian report as the ID when this motor is connected

Type:

return

property default_constants: DefaultConstants

Default controller configuration

Type:

return

property default_acceleration_limit: int

class Identification

Bases: object

Results of auto-detection

property device_type: DeviceClass

Detected device class (portMode must not be POWER_OFF)

Type:

return

property device_class: DeviceType

More detailed device type

Type:

return

class DefaultConstants

Bases: object

Control loop parameters that are typically not changed much

property motor: Motor

property controller: Controller

property observer: Observer

class Motor

Bases: object

Linear dynamic model of the connected motor. This model can be used for estimating various internal states of the motor.

property Kt_NmPerA: float

Torque constant, in N*m/A

Type:

return

property Kb_VPerRadPerSec: float

Torque constant in V/(rad/sec)

Type:

return

property B_NmPerRadPerSec: float

Friction constant, in N*m/(rad/sec)

Type:

return

property Udeadzone_Volts: float

Voltage needed to make the motor moves

Type:

return

property R_Ohm: float

Armature resistance, in ohms

Type:

return

property L_Henry: float

Armature inductance, in henry

Type:

return

property Cp_Farad: float

Capacity of a EMI-eliminating capacitor across motor terminals, in farads

Type:

return

property ticksPerRevolution: float

Number of encoder ticks per one revolution.

Type:

return

class Controller

Bases: object

Constants of the position/speed controller Brian implements these two controllers: - a parallel-form 2-degrees-of-freedom PI controller for motor speed [1], and - a cascaded P controller for motor position. [1]: https://www.mathworks.com/help/control/ug/two-degree-of-freedom-2-dof-pid-controllers.html

property speedKp: float

Proportional constant of the speed PI controller

Type:

return

property speedKi: float

Integral constant of the speed PI controller

Type:

return

property speedBeta: float

Setpoint weight in the proportional branch of the PI controller (see [1])

Type:

return

property positionKp: float

Proportional constant of the cascaded position P controller (its output is target speed in ticks/s)

Type:

return

property positionToleranceTicks: int

Tolerate up to this deviation with zero output (needed for EV3 medium motor)

Type:

return

class Observer

Bases: object

Additional configuration of state observer.

property current: Current

Current

property speed: Speed

Speed

class Current

Bases: object

Current observer parameters. Brian has to estimate motor winding current from H-bridge current measurements. These are not equal (PWM=0 makes the winding current impossible to directly measure). The way it does so is by simulating the current response using the provided model and then correcting the predicted value using real measurements (when they’re available).

property measurementWeight_pct: int

Correction step: How much weight to give to measurements vs. model prediction

Type:

return

property minimumPwmOnTime_pct: int

Only trust measurements if the PWM has at least this duty cycle

Type:

return

class Speed

Bases: object

Speed tracking loop parameters Brian estimates motor speed using a tracking loop/observer inspired by figure 3 and equations (6) in [2]. These constants specify the parameters of the loop. [2]: https://www.sciencedirect.com/science/article/pii/S2405896319326618

property Kp: int

property Ki: int