Motion-Based Piloted Simulation Evaluation of a Control Allocation Technique to Recover from Pilot Induced Oscillations

Abstract

This paper describes the maturation of a control allocation technique designed to assist pilots in the recovery from pilot induced oscillations (PIOs). The Control Allocation technique to recover from Pilot Induced Oscillations (CAPIO) is designed to enable next generation high efficiency aircraft designs. Energy efficient next generation aircraft require feedback control strategies that will enable lowering the actuator rate limit requirements for optimal airframe design. One of the common issues flying with actuator rate limits is PIOs caused by the phase lag between the pilot inputs and control surface response. CAPIO utilizes real-time optimization for control allocation to eliminate phase lag in the system caused by control surface rate limiting. System impacts of the control allocator were assessed through a piloted simulation evaluation of a non-linear aircraft simulation in the NASA Ames Vertical Motion Simulator. Results indicate that CAPIO helps reduce oscillatory behavior, including the severity and duration of PIOs, introduced by control surface rate limiting.

Real-Time Optimization for use in a Control Allocation System to Recover from Pilot Induced Oscillations

“…Results from the simulation evaluation confirm that the CAPIO system successfully contributed to a reduction in the severity and duration of PIOs, and to an improvement in the pilots' perception of PIO tendencies and in the pilots' PIO ratings, as compared to the baseline allocator. 28 As noted in 28, further maturation of the CAPIO system is needed to enable lowering the actuator rate limit requirements. Analytical studies are needed to enhance and guarantee the closed-loop stability properties of an aircraft, and to extend the CAPIO system to influence and improve overall system characteristics.…”

“…As a diagonal element of W d changes from zero to a positive value and returns to zero, the derivative following behavior of the CAPIO allocator is engaged and disengaged, respectively. 28 The objective function q can be written in terms of a positive-definite Hessian as follows:…”

“…Detailed results from the piloted simulation in VMS are discussed in Ref. 28. A brief summary of the accomplishment including the real time impact of the CAPIO System and the applicability of this research to future experiments is given in Sect.…”

A phase compensator to prevent pilot induced oscillations by actuator rate limiting

“…These approaches include differentiate-limit-integrate (DLI) approach [9~12], phase compensation [13], linear or nonlinear reference filtering [14], Antiwindup type [15] and control allocation technique approach [16~18]. Among these approaches, control allocation technique to recover from pilot induced oscillations (CAPIO) is one of the first known techniques to address the problems that arise from stringent actuator rate limits for multiinput, multi-output (MIMO) applications without the use of ganging [18]. This paper further investigates the control allocation technique to the actuator rate-limit problem.…”