Tactile Limit Cueing Systems for Rotorcraft Flight Control

Abstract

The purpose of this research project was to investigate technologies which may be applied to a tactile limit cueing system, and to design, build and test a tactile limit cueing demonstrator based on one of those technologies. The project looked at using the holding torque of a hybrid stepper motor to provide a resistive torque to a control stick. However, there is a ratcheting effect felt when the stepper motor shaft passes through different steps. The project measures this ratcheting effect and considers the viability of this technology as a tactile cueing system for a pilot. The prototype for this system was constructed with a cyclic (control stick) constrained to move in 1-axis. A stepper motor and gearbox was attached to the pivot point of the cyclic to provide the resistive torque. The results confirmed an increase in the holding torque of the stepper motor as the current to its windings increased and also showed that the average torque ripple measured as the motor shaft was actuated, was independent of the current input into the stepper motor.