HELIOP - Helicopter Shipdeck Operations

Operating helicopter from sea-based platforms is a challenging endeavor due to different factors, like influence of the landing zone on pilot performance, limited field of view during landing maneuver, and degraded visual environment (DVE). To localize the moving restricted landing area and approach safe, pilots have to compensate ship motion in all axes and heave motions of the landing area, as well as ship forward speed and recirculating ship airwake. Different characteristics of Helicopter Shipdeck Operations (HELIOP) are under exploration at the Institute of Helicopter Technology due to different topics.

By using a see-through Head-Mounted Display (HMD) with predictive augmentation modes, displaying needed information in visual conformal manner - for instance parameters of the flight path - enables to enhance pilot assistance systems. The restricted landing area necessitates precise maneuvering to avoid nearby structures of the ship. Existing systems for visual aids in maritime operations have to deal with different challenges due to not interfere with other instrumentation or overload the pilot with information. According to the complex mission task elements, deceleration, hover, ensuing side step and land, a pilot fitted augmented reality based HMD symbology format for the deck-landing task is focus of the HMI development. Investigations focus on the design of a HMD based predictive augmentation model containing a control model to perform a safe landing on the ship deck.

Predictive augmentation model is harmonized with control laws for autonomous guidance of a helicopter to a moving shipdeck. Higher control modes are essential to relieve pilot workload and enable autonomous shipdeck recovery. Investigations in helicopter shipdeck landing also focuses on control laws for fully autonomous approach guidance from cruise to relative hover on a moving shipdeck. First, the engagement geometry of a typical helicopter-ship combination is described. An instrument-like procedure including arrival and approach phases is defined and the necessary conditions for successful guidance based on ground track, altitude and ground speed parameters are specified. Second, outer loop control laws for real-time generation of the flight path vector commands are developed. The control laws use state feedback from the helicopter-ship system. Control gains are defined in terms of the distance to next waypoint to achieve smooth and gradual state tracking. Third, a model-based inner loop control is implemented to command the required collective, cyclic and pedal inputs for accurate flight path vector tracking, stabilization and axes cross-coupling compensation tasks.

Pilot-in-the-loop simulations are performed with the Rotorcraft Simulation Environment (ROSIE) to evaluate display concepts and control mechanism under simulated different environmental conditions.