[AUTONAVx][lec4] PID Control

1D PD control

class UserCode:
    def __init__(self):
        # TODO: tune gains
        self.Kp = 1.4
        self.Kd = 3.0
        self.last_x = 0.0

    def compute_control_command(self, t, dt, x_measured, x_desired):
        ''' :param t: time since simulation start :param dt: time since last call to compute_control_command :param x_measured: measured position (scalar) :param x_desired: desired position (scalar) :return - control command u '''
        # TODO: implement PD controller
        u = self.Kp*(x_desired-x_measured)+self.Kd*(0-(x_measured-self.last_x)/dt)
        self.last_x = x_measured
        return u

3D PD Control

import numpy as np

class State:
    def __init__(self):
        self.position = np.zeros((3,1))
        self.velocity = np.zeros((3,1))

class UserCode:
    def __init__(self):
        # TODO: tune gains

        # xy control gains
        Kp_xy = 2 # xy proportional
        Kd_xy = 1 # xy differential

        # height control gains
        Kp_z  = 0.2 # z proportional
        Kd_z  = 1.0 # z differential

        self.Kp = np.array([[Kp_xy, Kp_xy, Kp_z]]).T
        self.Kd = np.array([[Kd_xy, Kd_xy, Kd_z]]).T


    def compute_control_command(self, t, dt, state, state_desired):
        ''' :param t: time since simulation start :param dt: time since last call to measurement_callback :param state: State - current quadrotor position and velocity computed from noisy measurements :param state_desired: State - desired quadrotor position and velocity :return - xyz velocity control signal represented as 3x1 numpy array '''
        # plot current state and desired setpoint
        self.plot(state.position, state_desired.position)

        # TODO: implement PID controller computing u from state and state_desired
        u = self.Kp*(state_desired.position-state.position)+\
        self.Kd*(state_desired.velocity-state.velocity)
        return u

    def plot(self, position, position_desired):
        from plot import plot
        plot("x", position[0])
        plot("x_des", position_desired[0])
        plot("y", position[1])
        plot("y_des", position_desired[1])
        plot("z", position[2])
        plot("z_des", position_desired[2])
        plot("z_des", position_desired[2])