Trajectory tracking controllers for rotorcraft unmanned aerial vehicles (UAVS)
Apparatus, systems, methods, and articles of manufacture for tracking a trajectory by rotorcraft unmanned aerial vehicles (UAVs) are described herein. An example trajectory tracking controller includes an altitude controller to calculate an output value of a thrust control variable based on a trajectory of a rotorcraft independent of one or more system parameters of the rotorcraft. The example trajectory tracking controller also includes an attitude controller to calculate output values of roll, pitch, and yaw control variables based on the trajectory independent of the one or more of the system parameters. The example trajectory tracking controller further includes a motor speed selector to select speeds for propeller motors of the rotorcraft based on the output values of the thrust, roll, pitch, and yaw control variables and activate the propeller motors based on the selected motor speeds.
1. A trajectory tracking controller comprising:
an altitude controller to calculate an output value of a thrust control variable based on a trajectory of a rotorcraft independent of one or more system parameters of the rotorcraft;
an attitude controller to calculate output values of roll, pitch, and yaw control variables based on the trajectory independent of the one or more of the system parameters; and
a motor speed selector to select speeds for propeller motors of the rotorcraft based on the output values of the thrust, roll, pitch, and yaw control variables and activate the propeller motors based on the selected motor speeds, wherein, at a frequency of at least about 500 Hertz (Hz), the altitude controller is to recalculate the output value for the thrust control variable, the attitude controller is to recalculate the output values for the roll, pitch, and yaw control variables, and the motor speed selector is to select the motor speeds and activate the propeller motors.
2. The controller of claim 1 , wherein the motor speed selector is to select the motor speeds from a table of a plurality of motor speed configurations, the motor speed configurations corresponding to different combinations of the output values of the thrust, roll, pitch, and yaw control variables.
3. The controller of claim 2 , wherein, for each of the motor speed configurations, each of the motor speeds is different.
4. The controller of claim 2 , wherein the motor speeds are selected from a plurality of discrete speed values for each of the propeller motors.
5. The controller of claim 4 , wherein the motor speeds are selected from eight discrete speed values for each of the propeller motors.
6. The controller of claim 1 , wherein each of the thrust, roll, pitch, and yaw control variables are one of two output values.
7. A trajectory tracking controller comprising:
an altitude controller to calculate an output value of a thrust control variable based on a trajectory of a rotorcraft independent of one or more system parameters of the rotorcraft, the system parameters including at least one of a mass of the rotorcraft, moments of inertia of the rotorcraft, a drag coefficient of the propeller motors, a thrust coefficient of the propeller motors, or a distance between the propeller motors and a center of mass of the rotorcraft;
an attitude controller to calculate output values of roll, pitch, and yaw control variables based on the trajectory independent of the one or more of the system parameters; and
a motor speed selector to select speeds for propeller motors of the rotorcraft based on the output values of the thrust, roll, pitch, and yaw control variables and activate the propeller motors based on the selected motor speeds.
8. The controller of claim 7 , wherein the output values of the thrust, roll, pitch, and yaw control variables are calculated independent of the mass of the rotorcraft, the moments of inertia of the rotorcraft, the drag coefficient of the propeller motors, the thrust coefficient of the propeller motors, and the distance between the propeller motors and the center of mass of the rotorcraft.
9. A non-transitory machine readable storage medium comprising instructions that, when executed, cause a machine to at least:
calculate output values for thrust, roll, pitch, and yaw control variables based on a trajectory of a rotorcraft independent of one or more system parameters of the rotorcraft, the system parameters including at least one of a mass of the rotorcraft, moments of inertia of the rotorcraft, a drag coefficient of the propeller motors, a thrust coefficient of the propeller motors, or a distance between the propeller motors and a center of mass of the rotorcraft;
select motor speeds for propeller motors of the rotorcraft based on the output values for the thrust, roll, pitch, and yaw control variables; and
activate the propeller motors based on the selected motor speeds.
10. The non-transitory machine readable storage medium of claim 9 , wherein the instructions, when executed, cause the machine to calculate the output values of the thrust, roll, pitch, and yaw control variables independent of the mass of the rotorcraft, the moments of inertia of the rotorcraft, the drag coefficient of the propeller motors, the thrust coefficient of the propeller motors, and the distance between the propeller motors and the center of mass of the rotorcraft.
11. The non-transitory machine readable storage medium of claim 9 , wherein the instructions, when executed, further cause the machine to determine a roll reference trajectory and a pitch reference trajectory to be performed to navigate the rotorcraft along the trajectory, and wherein the calculation of the output value of the roll control variable is based on the roll reference trajectory and the calculation of the output value of the pitch control variable is based on the pitch reference trajectory.
12. The non-transitory machine readable storage medium of claim 11 , wherein the instructions, when executed, cause the machine to calculate the output value of the yaw control variable based on a yaw reference trajectory.
13. The non-transitory machine readable storage medium of claim 11 , wherein the instructions, when executed, further cause the machine to determine, based on a current position of the rotorcraft and a desired position of the trajectory, forces to be generated along x, y, z axes by the rotorcraft to follow the trajectory, and wherein the determination of the roll reference trajectory and the pitch reference trajectory are based on the forces to be generated along the x, y, z axes.
14. The non-transitory machine readable storage medium of claim 13 , wherein the instructions, when executed, cause the machine to calculate the thrust control variable based on a z reference signal of the desired position of the trajectory.
15. The non-transitory machine readable storage medium of claim 13 , wherein instructions, when executed, further cause the machine to determine, based on the current position of the rotorcraft and the desired position of the trajectory, one or more disturbance rejection control laws, and wherein the calculation of the forces to be generated along the x, y, z axes uses the disturbance rejection control laws to eliminate disturbances from an inertial measurement unit of the rotorcraft.