Investigation of Reaction Control System Design on Spacecraft Handling Qualities for Docking

A program of research, development, test, and evaluation is planned for the development of spacecraft handling qualities guidelines. In this first experiment, the effects of reaction control system design characteristics and rotational control laws were evaluated during simulated proximity operations and docking. Also, the influence of piloting demands resulting from varying closure rates was assessed. The pilot-in-the-loop simulation results showed that significantly different spacecraft handling qualities result from the design of the reaction control system. In particular, cross coupling between translational and rotational motions significantly affected handling qualities as reflected by Cooper-Harper pilot ratings and pilot workload, as reflected by Task Load Index ratings. This influence is masked (but only slightly) by the rotational control system mode. Although rotational control augmentation using rate command/attitude hold can reduce the workload (principally, physical workload) created by cross coupling, the handling qualities are not significantly improved. The attitude and rate deadbands of the rate command/attitude hold introduced significant mental workload and control compensation to evaluate when deadband firings would occur, assess their impact on docking performance, and apply control inputs to mitigate that impact.