Simulation of automatic helicopter deck landings using nature inspired flight control

Abstract

NOMENCLATURE k variable describing profile of motion [-] p, q, r angular roll, pitch and yaw rates in aircraft body axes [deg/s] Q e engine torque [Nm] t time [s] T total duration time of motion [s] x, y, z position [m] Greek notation φ, θ, Ψ Euler angles, describing aircraft attitude [deg] θ 0 , θ 0,tr main rotor and tail rotor collective pitch [deg] θ 1s , θ 1s lateral and longitudinal cyclic pitch [deg] χ gap [m, deg, N, etc.] τ time to close a gap [s] Ω main rotor rotational speed [%] Χ state [m, deg, etc.] ABSTRACTResearch studies have indicated that the optical flow parameter, time to close tau, is the basis of purposeful control in the animal world, and used by both fixed wing and helicopter pilots during manoeuvring. This parameter is defined as the instantaneous time to close a gap (spatial or force) at the current closing rate. A novel automatic flight control strategy has been developed that makes use of optical flow theory and in particular, the parameter tau. This strategy has been applied to two distinct problems; (1) the landing of a helicopter on a ship and (2) the lateral repositioning of a helicopter. The first is a challenging case because the landing of a helicopter on a ship is one of the most dangerous of all helicopter flight operations. Furthermore, helicopters are often subject to torque oscillations during rapid collective control, which increases pilot workload significantly when operating with low power margins and/or whilst performing tasks that require accurate heave control. The second case demonstrates the generality of the technique. Both automatic manoeuvres were simulated successfully within desired limits, with the novel control strategy creating a 'natural', smooth, tau motion.

Optic Flow Regulation in Unsteady Environments: A Tethered MAV Achieves Terrain Following and Targeted Landing Over a Moving Platform

“…This would make the system hardly compatible with MAVs in the 100-milligram to 100-gram range [8][9][10][11]. Some authors have simulated an automatic landing system that generates a decking trajectory in an advanced rotorcraft environment (called FLIGHTLAB): this trajectory is the one that would be presumably taken by a human pilot on the basis of optic flow (OF) cues [12]. But here again, the trajectory was computed via the classical position and attitude data available onboard, without visually measuring the OF directly.…”

Development of a Generic Time-to-Contact Pilot Guidance Model

“…[25] or, for example, Hess's pursuit tracking pilot model [31]. This more appropriately reflects the hypothesis that τ information is perceived directly by the pilot, without the need for intermediate reasoning or computation.…”

“…[23] studied pilot guidance strategy using an adaptive pilot model (APM) when performing the ADS-33 Acceleration-Deceleration maneuver. Reference [25] reported the development of a τ-following controller for automatic helicopter deck landings. However, despite notionally being studies into the use of τ, neither explicitly used τ within the control loops developed.…”

The tau of flight control

“…radar altitude, localiser and glide slope; so τ and its derivatives were not sensed but rather derived from conventional 548 THE AERONAUTICAL JOURNAL SEPTEMBER 2011 Figure 45. Control law concept for a τ g following feedback controller (85) .…”

“…The boundaries of the PADFIELD THE TAU OF FLIGHT CONTROL 549 Figure 46. Lateral flight path trajectory during an automated lateral re-position manoeuvre (85) . Figure 47.…”