frc971/control_loops/python/cim.py

#!/usr/bin/python

from frc971.control_loops.python import control_loop
import numpy


class CIM(control_loop.ControlLoop):

    def __init__(self):
        super(CIM, self).__init__("CIM")
        # Stall Torque in N m
        self.stall_torque = 2.42
        # Stall Current in Amps
        self.stall_current = 133
        # Free Speed in RPM
        self.free_speed = 4650.0
        # Free Current in Amps
        self.free_current = 2.7
        # Moment of inertia of the CIM in kg m^2
        self.J = 0.0001
        # Resistance of the motor, divided by 2 to account for the 2 motors
        self.resistance = 12.0 / self.stall_current
        # Motor velocity constant
        self.Kv = ((self.free_speed / 60.0 * 2.0 * numpy.pi) /
                   (12.0 - self.resistance * self.free_current))
        # Torque constant
        self.Kt = self.stall_torque / self.stall_current
        # Control loop time step
        self.dt = 0.005

        # State feedback matrices
        self.A_continuous = numpy.matrix(
            [[-self.Kt / self.Kv / (self.J * self.resistance)]])
        self.B_continuous = numpy.matrix(
            [[self.Kt / (self.J * self.resistance)]])
        self.C = numpy.matrix([[1]])
        self.D = numpy.matrix([[0]])

        self.A, self.B = self.ContinuousToDiscrete(self.A_continuous,
                                                   self.B_continuous, self.dt)

        self.PlaceControllerPoles([0.01])
        self.PlaceObserverPoles([0.01])

        self.U_max = numpy.matrix([[12.0]])
        self.U_min = numpy.matrix([[-12.0]])

        self.InitializeState()