The mass of the quadrotor consists of two parts: the central mass and the mass associated with the four propulsion systems of the body. Thus, the variable bodyCenter represents the mass located in the center of the quadrotor, while body1, body2, body3 and body4 represent the mass of the four propulsion systems. It is assumed that the arms themselves have no mass. The numbering with respect to the body reference frame is illustrated in Figure 1. The total mass of the drone, represented by "droneMass," is calculated by adding the masses of the "bodyCenter," "body1," "body2," "body3" and "body4. The mass and inertia properties of the propulsion systems are the same in all four bodies and can be set at the top level.

Geometry

The arm length parameter determines the distance between the center of the mass of the quadrotor and the center of the mass of each propulsion system. 

Propulsion 

The propulsion connector serves as a mounting point for the motor and propeller, connecting them to the DC motor and propeller through the frame connector to support torque generation and the rotation of the propeller within the Quadrotor model.

Animation

By default, the Modelica Standard Library FixedShape primitives are used to visualize different components with simple box and cylinder shapes with the dimensions given in the Geometry parameters and by estimating them for certain components. A CAD model of the quadrotor case (chassis) is used for animation, and one can replace them with another CAD file with the .obj extend. It can be used by setting CADshapes as true and entering the path of the .obj file to CADpath field. This automatically disables the default animation in every component. The rotation and translation between the CAD object of the chassis and the propeller can be set up by modifying the r_Shape and lengthDirection parameters.

Connectors

This model contains a frame connected to the quadrotor body case (chassis) center of the mass and four other frames connected to the propulsion system in which the forces and torques of each propulsion system are mounted.