Passive rotor control mechanism for micro air vehicles
Technology for achieving the behavior and benefits of traditional cyclic control in one rotor may be implemented with a simple under-actuated passive mechanism. An air vehicle employing the disclosed technology maintains lifting thrust by regulating the average rotor speed and generates control moments through coordinated pulsing of the motor torque. Rapid pulsing of the motor torque induces oscillations in propeller angle of attack, and so causes “cyclic control” without requiring the traditional auxiliary actuators and linkages. The MAV propulsion system is capable of using a minimum number of actuators in dual roles of thrust and moment objectives.
1. An aerial vehicle comprising:
a hub;
a motor;
a motor shaft connected with the motor and the hub;
a rotor, wherein the motor shaft transmits torque to the rotor, wherein the torque of the motor is pulsed to generate control moments for the aerial vehicle; and
a first propeller blade attached to the hub via a first hinge and a second propeller blade attached to the hub via a second hinge, wherein the first hinge and the second hinge are appropriately placed to help generate control moments.
2. The aerial vehicle of claim 1 , wherein an axis of the first hinge and an axis of the second hinge are parallel with each other contained within a vertical plane containing an axis of the motor.
3. The aerial vehicle of claim 1 , wherein an axis of the first hinge and an axis of the second hinge are skewed out of a plane to affect a coupling between lead-lag motion and flap motion in order to induce changes in aerodynamic angle of attack.
4. The aerial vehicle of claim 1 , further comprising a flapping hinge, wherein the flapping hinge is connected between the hub and the first hinge or between the first hinge and the first propeller blade.
5. The aerial vehicle of claim 1 , further comprising:
a propeller blade attached to the hub, wherein the propeller blade is appropriately flexible to help generate control moments.
6. The aerial vehicle of claim 1 , wherein the control moments are based on an estimate of a position of the rotor.
7. The aerial vehicle of claim 6 , wherein the estimate of the position of the rotor is based on direct measurement using a high resolution magnetic encoder.
8. The aerial vehicle of claim 6 , wherein the estimate of the position of the rotor is based on an output of an observer algorithm working on a measured motion of the aerial vehicle and commanded attitude corrections.
9. The aerial vehicle of claim 6 , wherein the estimate of the position of the rotor is based on interpolating between once-per-revolution indexes from a device using timing.
10. The aerial vehicle of claim 6 , wherein the estimate of the position of the rotor is based on interpolating between once-per-revolution indexes from a device using a known commutation speed of the motor of the aerial vehicle.
11. The aerial vehicle of claim 10 , wherein the device is a mechanical device.
12. The aerial vehicle of claim 10 , wherein the device is an optical device.
13. The aerial vehicle of claim 10 , wherein the device is a magnetic device.
14. The aerial vehicle of claim 1 , wherein the rotor comprises a first hinge with a first axis and a second hinge with a second axis, wherein the first axis is parallel with the second axis and asymmetrical about the center.