Contents
How to calculate angular velocity of a quadcopter?
In order to convert these angular velocities into the angular velocity vector, we can use the following relation: ω = [1 0 − sθ 0 cϕ cθsϕ 0 − sϕ cθcϕ]˙θ where ω is the angular velocity vector in the body frame. We can relate the body and inertial frame by a rotation matrix R which goes from the body frame to the inertial frame.
How to describe the linear motion of a quadcopter?
Thus, the linear motion can be summarized as m¨x = [ 0 0 − mg] + RTB + FD where →x is the position of the quadcopter, g is the acceleration due to gravity, FD is the drag force, and TB is the thrust vector in the body frame.
How is the angle of attack of a quadcopter modulated?
In order to produce a torque the angle of attack is modulated by the location of each rotor in each stroke, such that more thrust is produced on one side of the rotor plane than the other. The complicated design of the rotor and swashplate mechanism presents some problems, increasing construction costs and design complexity.
Is it possible to control a quadcopter by itself?
The decreasing cost of modern microprocessors has made electronic and even completely autonomous control of quadcopters feasible for commercial, military, and even hobbyist purposes. Quadcopter control is a fundamentally difficult and interesting problem.
How is the position of a quadrotor determined?
This notation uses notation taken from the aeronautics literature, specifically the North, East, Down (NED) coordinate system. The position of the quadrotor is given in the global frame while the velocity and angular velocity are defined in the quadrotor body frame.
How are the angular rates of a quadrotor calculated?
If the Euler angles are assumed to be small (near 0), then the S matrix becomes the identity matrix and the angular rates are roughly equal to the time derivative of the Euler angles. Quadrotors use varying types of brushless motors to generate the thrust and torques needed to control the platform.
How many degrees of freedom does a quadrotor have?
The quadrotor is classified as an under-actuated system. While the quadrotor can move in 6 degrees of freedom (3 translational and 3 rotational), there are only 4 inputs that can be controlled (the speeds of the 4 motors). As will be shown below, the rotational and translational dynamics are coupled which presents an interesting control problem.