Method of piloting a rotary wing drone having multiple rotors

A method of controlling a rotary-wing drone having multiple rotors driven by respective individually-controllable motors for controlling the drone in attitude and in speed,

• the method being a method for implementing a transition:
• from a moving state at an initial instant in which the drone is flying with a non-zero horizontal linear speed and a non-zero angle of tilt relative to the horizontal;
• to a hovering state at a final instant in which the drone has a zero horizontal linear speed and a zero angle of inclination;
• the method being characterized by the steps consisting in:
• a) acquiring initial measurements representative of the components of the horizontal linear speed, of the tilt angles, and of the angular speeds at the initial instant;
• b) setting a value for stopping time between the initial instant and the final instant;
• c) on the basis of the initial measurements acquired in step a) and of the stopping time set in step b), parameterizing a predetermined predictive function that models optimum continuous decreasing variation in the horizontal linear speed as a function of time from the speed at the initial instant to a zero speed at the end of the set time;
• d) generating setpoint values for a loop for controlling the motors of the drone, these setpoint values corresponding to a precalculated target horizontal linear speed, at a given instant, on the basis of the predictive function as parameterized in step c);
• and
• e) once the hovering state has been reached, activating a hovering flight control loop suitable for stabilizing the drone with a zero horizontal linear speed and a zero tilt angle relative to the ground;
• wherein the predetermined predictive function is a polynomial function, and the step c) of parameterizing the function is a step of determining the coefficients of the polynomial, and further wherein the polynomial function is a function:
• u(t)=(T−t)3*(au*t+bu)
• v(t)=(T−t)3*(av*t+bv)
• where:
• u(t) is one of the components of the precalculated target horizontal linear speed;
• v(t) is the other component of the precalculated target horizontal linear speed;
• T is the value of the stopping time set in step b);
• and
• au, bu, av, and bv are the coefficients of the polynomial as determined in step c).