Fuzzy logic-based control method for helicopters carrying suspended loads

• US 8,185,259 B2
• Filed: 08/23/2010
• Issued: 05/22/2012
• Est. Priority Date: 08/23/2010
• Status: Expired due to Fees

• Current Assignee: King Fahd University of Petroleum & Minerals (Government of Saudi Arabia)
• Original Assignee: King Fahd University of Petroleum & Minerals (Government of Saudi Arabia)
• Inventors: Omar, Hanafy M.
• Primary Examiner(s): Mawari, Redhwan k
• Application Number:
  US12/861,502
• Publication Number:
  US 20120046810A1
• Time in Patent Office: 638 Days
• Field of Search: 701/3, 701/4, 701/27, 701/40, 701/44, 701/46, 701/57, 701/58, 701/60, 701/10, 244/17.11, 244/3, 244/26, 244/164, 244/171, 706/2, 706/3, 706/4, 706/5, 706/6, 706/13, 706/903, 706/905, 706/913, 700/28, 700/29, 700/48, 700/50, 700/54, 700/55
• US Class Current: 701/3
• CPC Class Codes: G05D 1/063 by acting on the motors

Abstract

The fuzzy logic-based control method for helicopters carrying suspended loads utilizes a controller based on fuzzy logic membership distributions of sets of load swing angles. The anti-swing controller is fuzzy-based and has controller outputs that include additional displacements added to the helicopter trajectory in the longitudinal and lateral directions. This simple implementation requires only a small modification to the software of the helicopter position controller. The membership functions govern control parameters that are optimized using a particle swarm algorithm. The rules of the anti-swing controller are derived to mimic the performance of a time-delayed feedback controller. A tracking controller stabilizes the helicopter and tracks the trajectory generated by the anti-swing controller.

Claims

1. A fuzzy logic-based control method for a helicopter carrying a suspended load, comprising the steps of:

providing a helicopter attitude and position tracking controller, the controller being designed to generate outputs for stabilizing the helicopter while accepting tracking commands from a reference source and displacement commands from a feedback source as inputs, the design including feedback gain (k) based on minimizing a load swing history, wherein the load swing history is represented by a Linear Quadratic Regulator method, the Linear Quadratic Regulator method depending on minimizing the quadratic function,

2. The fuzzy logic-based control method according to claim 1, wherein said evolutionary computation algorithm is a particle swarm optimization algorithm.

3. The fuzzy logic-based control method according to claim 1, further comprising configuring five of the membership functions corresponding to the θ

_L input, the five membership functions including Negative Big (NB), Negative Small (NS), Zero (ZO), Positive Small (PS) and Positive Big (PB), wherein at least two of the membership functions overlap.

4. The fuzzy logic-based control method according to claim 3, further comprising the steps of:

overlapping the NS membership function with the NB membership function;

overlapping the Z0 membership function with the NS membership function;

overlapping the PS membership function with the ZO membership function; and

overlapping the PB membership function with the PS membership function.

5. The fuzzy logic-based control method according to claim 1, further comprising the step of configuring three of said membership functions corresponding to said θ

_L rateinput, said three membership functions including Negative Big (NB), Zero (ZO), and Positive Big (PB), wherein at least two of said membership functions overlap.

6. The fuzzy logic-based control method according to claim 5, further comprising the steps of:

overlapping the ZO membership function with the NB membership function; and

overlapping the PB membership function with the ZO membership function.

7. The fuzzy logic-based control method according to claim 1, further comprising the step of configuring three of the membership functions corresponding to one of the displacementoutputs, the three membership functions including Negative Big (NB), Zero (ZO), and Positive Big (PB), wherein at least two of the membership functions overlap.

8. The fuzzy logic-based control method according to claim 7, further comprising the steps of:

overlapping the ZO membership function with the NB membership function; and

overlapping the PB membership function with the ZO membership function.

9. The fuzzy logic-based control method according to claim 1, further comprising the steps of:

assigning ranges to the normalized membership functions; and

using scaling factors to transform the ranges of the normalized membership functions to physical operating ranges based on a maximum value of the load swings and a maximum value of the helicopter displacements.

10. A computer software product, comprising a non-transitory storage medium readable by a processor, the medium having stored thereon a set of instructions for issuing displacement control commands to a helicopter carrying a suspended load while in hover flight, the set of instructions including:

(a) a first sequence of instructions which, when executed by the processor, causes said processor to configure a helicopter attitude and position tracking controller, the helicopter attitude and position tracking controller being designed to generate outputs for stabilizing the helicopter while accepting tracking commands from a reference source and displacement commands from a feedback source as inputs, the design configuration including feedback gain k based on minimizing a load swing history, wherein the load swing history is represented by a Linear Quadratic Regulator method, the Linear Quadratic Regulator method depending on minimizing the quadratic function;

11. The computer software product according to claim 10 wherein said evolutionary computation algorithm is a particle swarm optimization algorithm.

12. The computer software product according to claim 10, wherein the set of instructions further comprises:

(f) a sixth sequence of instructions which, when executed by the processor, causes said processor to configure five of the membership functions corresponding to the θ

_L input, the five membership functions including Negative Big (NB), Negative Small (NS), Zero (ZO), Positive Small (PS) and Positive Big (PB), wherein at least two of the membership functions overlap.

13. The computer software product according to claim 12, wherein the set of instructions further comprises:

(g) a seventh sequence of instructions which, when executed by the processor, causes said processor to;

overlap the NS membership function with the NB membership function;

overlap the Z0 membership function with the NS membership function;

overlap the PS membership function with the ZO membership function; and

overlap the PB membership function with the PS membership function.

14. The computer software product according to claim 10, wherein the set of instructions further comprises:

(h) an eighth sequence of instructions which, when executed by the processor, causes said processor to configure three of the membership functions corresponding to the θ

_L rateinput, the three membership functions including Negative Big (NB), Zero (ZO), and Positive Big (PB), wherein at least two of the membership functions overlap.

15. The computer software product according to claim 14, wherein the set of instructions further comprises:

(i) a ninth sequence of instructions which, when executed by the processor, causes said processor to;

overlap the ZO membership function with the NB membership function; and

overlap the PB membership function with said ZO membership function.

16. The computer software product according to claim 10, wherein the set of instructions further comprises:

(j) a tenth sequence of instructions which, when executed by the processor, causes said processor to configure three of the membership functions corresponding to one of the displacement outputs, the three membership functions including Negative Big (NB), Zero (ZO), and Positive Big (PB), wherein at least two of the membership functions overlap.

17. The computer software product according to claim 16, wherein the set of instructions further comprises:

(k) an eleventh sequence of instructions which, when executed by the processor, causes said processor to;

overlap the ZO membership function with the NB membership function; and

overlap the PB membership function with the ZO membership function.

18. The computer software product according to claim 10, wherein the set of instructions further comprises:

(I) a twelfth sequence of instructions which, when executed by the processor, causes said processor to assign ranges to the normalized membership functions; and

use scaling factors to transform the ranges of the normalized membership functions to physical operating ranges based on a maximum value of the load swings and a maximum value of the helicopter displacements.