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rotorpy/vehicles/crazyflie_params.py

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+"""
+Physical parameters for a quadrotor. Values parameterize the inertia, motor dynamics, 
+rotor aerodynamics, parasitic drag, and rotor placement. 
+Additional sources:
+    https://bitcraze.io/2015/02/measuring-propeller-rpm-part-3
+    https://wiki.bitcraze.io/misc:investigations:thrust
+    https://commons.erau.edu/cgi/viewcontent.cgi?article=2057&context=publication
+Notes:
+    k_thrust is inferred from 14.5 g thrust at 2500 rad/s
+    k_drag is mostly made up
+"""
+import numpy as np
+
+d = 0.043
+
+quad_params = {
+
+    # Inertial properties
+    'mass': 0.03,       # kg
+    'Ixx':  1.43e-5,    # kg*m^2
+    'Iyy':  1.43e-5,    # kg*m^2
+    'Izz':  2.89e-5,    # kg*m^2
+    'Ixy':  0.0,        # kg*m^2
+    'Iyz':  0.0,        # kg*m^2 
+    'Ixz':  0.0,        # kg*m^2
+
+    # Geometric properties, all vectors are relative to the center of mass.
+    'num_rotors': 4,                        # for looping over each actuator
+    # 'rotor_pos': {  
+    #                 'r1': np.array([0.046,  0,      0]),    # Location of Rotor 1, meters
+    #                 'r2': np.array([0,      0.046,  0]),    # Location of Rotor 2, meters
+    #                 'r3': np.array([-0.046, 0,      0]),    # Location of Rotor 3, meters
+    #                 'r4': np.array([0,      -0.046, 0]),    # Location of Rotor 4, meters
+    #              },
+    'rotor_pos': {  
+                    'r1': d*np.array([ 0.70710678118, 0.70710678118, 0]),    # Location of Rotor 1, meters
+                    'r2': d*np.array([ 0.70710678118,-0.70710678118, 0]),    # Location of Rotor 2, meters
+                    'r3': d*np.array([-0.70710678118,-0.70710678118, 0]),    # Location of Rotor 3, meters
+                    'r4': d*np.array([-0.70710678118, 0.70710678118, 0]),    # Location of Rotor 4, meters
+                 },
+
+    'rotor_directions': np.array([1,-1,1,-1]),  # This dictates the direction of the torque for each motor. 
+
+    'rI': np.array([0,0,0]), # location of the IMU sensor, meters
+
+    # Frame aerodynamic properties
+    'c_Dx': 0.5e-2,  # parasitic drag in body x axis, N/(m/s)**2
+    'c_Dy': 0.5e-2,  # parasitic drag in body y axis, N/(m/s)**2
+    'c_Dz': 1e-2,  # parasitic drag in body z axis, N/(m/s)**2
+
+    # Rotor properties
+    # See "System Identification of the Crazyflie 2.0 Nano Quadrocopter", Forster 2015.
+    'k_eta': 2.3e-08,           # thrust coefficient N/(rad/s)**2
+    'k_m':   7.8e-10,           # yaw moment coefficient Nm/(rad/s)**2
+    'k_d':   10.2506e-07,       # rotor drag coefficient N/(rad*m/s**2) = kg/rad
+    'k_z':   7.553e-07,         # induced inflow coefficient N/(rad*m/s**2) = kg/rad
+    'k_flap': 0.0,              # Flapping moment coefficient Nm/(rad*m/s**2) = kg*m/rad
+
+    # Motor properties
+    'tau_m': 0.005,           # motor response time, seconds
+    'rotor_speed_min': 0,       # rad/s
+    'rotor_speed_max': 2500,    # rad/s
+    'motor_noise_std': 100,     # rad/s
+
+}