Steady state differential roll moment control with automated differential lateral control

Patent metadata

Field	Value
Publication number	US-10329013-B2
Application number	US-201515513334-A
Country	US
Kind code	B2
Filing date	Sep 24, 2015
Priority date	Sep 25, 2014
Publication date	Jun 25, 2019
Grant date	Jun 25, 2019

Abstract

A method for controlling a differential rotor roll moment for a coaxial helicopter with rigid rotors, the method including receiving, with a processor, a signal indicative of a displacement command from a controller; receiving, with the processor via a sensor, one or more signals indicative of a longitudinal velocity, an angular velocity of one or more rotors and an air density ratio for the helicopter; determining, with the processor, a ganged collective mixing command in response to the receiving of the displacement command; determining, with the processor, a rotor advance ratio as a function of the longitudinal velocity and the angular velocity; and determining, with the processor, a corrective differential lateral cyclic command for the rigid rotors that controls the differential rotor roll moment to a desired value.

First claim

What is claimed is:

1. A method for controlling a differential rotor roll moment for a coaxial helicopter with rigid rotors, comprising:
receiving, with a processor, a signal indicative of a displacement command from a controller;
receiving, with the processor via a sensor, one or more signals indicative of a longitudinal velocity, an angular velocity of one or more rotors and an air density ratio for the helicopter;
determining, with the processor, a ganged collective mixing command in response to the receiving of the displacement command;
determining, with the processor, a rotor advance ratio as a function of the longitudinal velocity and the angular velocity;
determining, with the processor, a corrective differential lateral cyclic command by determining coefficients from the ganged collective mixing command, applying the coefficients to the rotor advance ratio to obtain a value and normalizing the value by the air density ratio; and
applying, with the processor, the corrective differential lateral cyclic command to the rigid rotors to control the differential rotor roll moment to a desired value.

2. The method of claim 1 , further comprising determining the corrective differential lateral cyclic command as a function of measured differential rolling moments and targeted differential rolling moments.

3. The method of claim 2 , further comprising varying the targeted differential rolling moment based upon aircraft flight condition, including at a minimum longitudinal velocity.

4. The method of claim 2 , further comprising determining an error value between the measured and targeted differential rolling moments.

5. The method of claim 1 , further comprising determining the corrective differential lateral cyclic command for rotor speeds above a predefined threshold value.

6. The method of claim 1 , further comprising determining the corrective differential lateral cyclic command as (i) a function of a gain of the rotor advance ratio and/or (ii) a function of upper and lower limits of differential lateral cyclic.

7. The method of claim 1 , further comprising determining a quantity of corrective differential lateral cyclic commands at different rotor speeds.

8. A control system for controlling a differential rotor roll moment for a coaxial helicopter with rigid rotors, comprising:
one or more sensors configured to determine a longitudinal velocity of the helicopter, an angular velocity of one or more rotors and an air density ratio for the helicopter;
one or more controllers configured to issue a displacement command during a flight maneuver; and
a computer operably connected to the one or more controllers and configured to:
determine a ganged collective mixing command in response to the displacement command;
determine a rotor advance ratio as a function of the longitudinal velocity and the angular velocity;
determine a corrective differential lateral cyclic command by determining coefficients from the ganged collective mixing command, applying the coefficients to the rotor advance ratio to obtain a value and normalizing the value by the air density ratio; and
apply the corrective differential lateral cyclic command for the rigid rotors to control the differential rotor roll moment to a desired value.

9. The control system of claim 8 , wherein the processor is configured to determine the corrective differential lateral cyclic command with a model which is a function of measured differential rolling moments and targeted differential rolling moments.

10. The control system of claim 9 , wherein the processor is configured to vary the targeted differential rolling moment based upon aircraft flight condition, including at a minimum longitudinal velocity.

11. The control system of claim 8 , wherein the processor is configured to determine an error value between the measured and targeted differential rolling moments.

12. The control system of claim 8 , wherein the processor is configured to determine the corrective differential lateral cyclic command for rotor speeds above a predefined threshold value.

13. The control system of claim 8 , wherein the processor is configured to determine the corrective differential lateral cyclic command as (i) a function of a gain of the rotor advance ratio and/or (ii) a function of upper and lower limits of differential lateral cyclic.

Assignees

• Sikorsky Aircraft Corp

Inventors

• Fegely Cody
• Eller Erez
• Wittmer Kenneth S
• Greenfield Aaron L
• Knag John

Classifications

• B64C27/80 Primary

  for differential adjustment of blade pitch between two or more lifting rotors · CPC title

• G05D1/0808

  specially adapted for aircraft · CPC title

• G05D1/0858

  specially adapted for vertical take-off of aircraft · CPC title

• B64C27/10

  arranged coaxially · CPC title