PASSIVE ROTOR CONTROL MECHANISM FOR MICRO AIR VEHICLES

• US 20160001877A1
• Filed: 03/14/2014
• Published: 01/07/2016
• Est. Priority Date: 03/14/2013
• Status: Active Grant

• Current Assignee: Trustees Of The University Of Pennsylvania (University of Pennsylvania)
• Original Assignee: Trustees Of The University Of Pennsylvania (University of Pennsylvania)
• Inventors: PAULOS, James J.
• Granted Patent: US 9,914,535 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B64C 27/008 Rotors tracking or balancing devices
• CPC Class Codes: B64C 27/12 Rotor drives
• CPC Class Codes: B64C 27/39 with individually articulated blades, i.e. with flapping or drag hinges
• CPC Class Codes: B64C 27/48 Root attachment to rotor head
• CPC Class Codes: B64C 27/57 automatic or condition responsive, e.g. responsive to rotor speed, torque or thrust
• CPC Class Codes: B64U 10/10 Rotorcrafts
• CPC Class Codes: B64U 10/17 Helicopters flying platforms B64U10/13
• CPC Class Codes: B64U 10/80 UAVs characterised by their small size, e.g. micro air vehicles [MAV]
• CPC Class Codes: B64U 30/20 Rotors; Rotor supports
• CPC Class Codes: B64U 30/29 Constructional aspects of rotors or rotor supports; Arrangements thereof
• CPC Class Codes: B64U 50/19 using electrically powered motors
• CPC Class Codes: H02P 2203/00 Indexing scheme relating to controlling arrangements characterised by the means for detecting the position of the rotor
• CPC Class Codes: H02P 7/29 using pulse modulation

Abstract

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.

Claims

1. A system comprising:

a motor;

a processor communicatively connected with the motor; and

a memory communicatively coupled with the processor, the memory having stored therein computer-readable instructions that, if executed by the processor, cause the processor to perform operations comprising;

regulating an average speed of a rotor of an aerial vehicle to maintain lifting thrust; and

pulsing of a torque of the motor of the aerial vehicle to generate control moments.

2. The system of claim 1, wherein the control moments are based on an estimate of a position of the rotor.

3. The system of claim 2, wherein the estimate of the position of the rotor is based on direct measurement using a high resolution magnetic encoder.

4. The system of claim 2, 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.

5. The system of claim 2, wherein the estimate of the position of the rotor is based on interpolating between once-per-revolution indexes from a device using timing.

6. The system of claim 2, 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.

7. The system of claim 6, wherein the device is a mechanical, an optical, or a magnetic device.

8. The system of claim 1, further operations comprising:

applying a signal comprising superimposing sinusoidal driving torque in phase with rotation of the rotor on top of a steady driving torque of the motor needed to balance drag of the rotor.

9. The system 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.

10. An aerial vehicle comprising:

a hub;

a motor;

a shaft connected with the motor and the hub; and

a rotor, wherein the shaft transmits torque to the rotor, wherein the torque of the motor is pulsed to generate control moments for the aerial vehicle.

11. The aerial vehicle of claim 10, further comprising:

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.

12. The aerial vehicle of claim 11, 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.

13. The aerial vehicle of claim 11, 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.

14. The aerial vehicle of claim 11, 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.

15. The aerial vehicle of claim 10, further comprising:

a propeller blade attached to the hub, wherein the propeller blade is appropriately flexible to help generate control moments.