Multi-rotor aircraft control

A method for controlling the flight of a multi-rotor aircraft having separate drive means for each rotor, each drive means being capable of separate control of rotor rpm and rotor blade pitch to achieve desired flight control effects;

• the method comprising:
• (I) an operator inputting commands to a multi-rotor aircraft control unit as control input,
• (II) the control unit processing the control input in at least one control module board, and
• (III) the control unit providing a resulting control output for at least three rotors;
• and
• wherein:
• (1) the multi-rotor aircraft has a yaw direction, a roll direction, a flip direction, the rotors have a collective pitch, and each rotor has an individual rotor pitch;
• (2) the control input to the control unit comprises yaw input, roll input, flip input, and collective pitch input;
• (3) the control output comprises individual rotor pitch control output, and provides at least yaw control, roll control, flip control, and collective pitch control of the multi-rotor aircraft;
• (4) the control module board comprises at least one mixing unit, and the control module board calculates individual rotor pitch for each rotor in the at least one mixing unit;
• (5) the control module board comprises at least one gyro, and receives from the at least one gyro proportional, input, derivative (PID) input comprising yaw PID input, roll PID input, and flip PID input;
• (6) the at least one mixing unit receives from the control module board at least:
• (i) yaw control output, including yaw PID output, (ii) roll control output, including roll PID output, (iii) flip control output, including flip PID output, and (iv) collective pitch output;
• (7) the control module board is configured to minimize operation in a region of collective pitch close to zero, where yaw performance is reduced as at least one individual rotor pitch crosses zero, by receiving the collective pitch input and generating therefrom the collective pitch output according to a relationship comprising a rapid transition region, wherein the rapid transition region is defined by at least two breakpoints marking a beginning and ending thereof, and wherein the collective pitch output moves rapidly between a positive collective pitch and a negative collective pitch within the rapid transition region with a relatively small, smooth change;
• and
• (8) the control module board is further configured to perform at least one of:
• (a) preventing undesired reversal of the yaw control, as a rotor torque response direction reverses, by reversing direction of the yaw control input, including the yaw PID input, when the collective pitch input is less than zero, thereby providing a corrected yaw control output, including yaw PID output, to the at least one mixing unit which calculates therefrom individual rotor pitch control output;
• (b) preventing undesired reversal of the yaw control, as a rotor torque response direction reverses, by reversing direction of the yaw control input, including the yaw PID input, for an individual rotor, when the individual rotor pitch is less than zero, thereby providing a corrected yaw control output, including yaw PID output, to the at least one mixing unit which calculates therefrom individual rotor pitch control output;
• (c) further receiving input from at least one force vector sensor, preventing undesired reversal of the yaw control, as a rotor torque response direction reverses, by (i) receiving from the at least one force vector sensor a lift force direction, being positive or negative, and (ii) reversing direction of the yaw control input, including the yaw PID input, when the lift force direction reverses, thereby providing a corrected yaw control output, including yaw PID output, to the at least one mixing unit which calculates therefrom individual rotor pitch control output.