D1-2.1 - Differential Torque Measurement Concept for Condition Monitoring of a Cycloidal Gearbox in a Flight Control Actuator

Event

23. ITG/GMA-Fachtagung Sensoren und Messsysteme 2026
2026-06-09 - 2026-06-10
Nürnberg

Band

Vorträge

Chapter

Kraft-, Drehmoment-, und Druck

Author(s)

M. Schmidt - DLR, Braunschweig

Pages

149 - 156

DOI

10.5162/sensoren2026/D1-2.1

ISBN

978-3-910600-11-9

Price

free

Abstract

Electromechanical actuators for primary flight control require reliable monitoring of transmission-related loads because the gearbox is a critical subsystem with wear-prone components and potential singlepoint failures. This paper presents a differential torque measurement concept for a Sumitomo cycloidal gearbox used in a flight control actuator. The approach is based on the simultaneous measurement of torque and rotational speed at the gearbox input and output in order to derive load-dependent loss characteristics and operating signatures of the drivetrain. For this purpose, a compact contactless torque measurement shaft was integrated between the motor and gearbox, while complementary sensor systems were used to acquire torque and position data at both measurement locations. The paper focuses on the measurement architecture, sensor integration, and experimental implementation on an EMA test bench. In addition, the acquired measurement data were combined with model-based fault models and simulation data to perform an initial condition-monitoring-oriented evaluation. Time- and frequency-domain analyses, including FFT and order tracking, were used to assess the sensitivity of the measured quantities to fault-related effects such as increased friction and backlash variation. The results indicate that the proposed measurement concept provides physically meaningful features for distinguishing relevant gearbox fault patterns and forms a promising basis for further conditionmonitoring investigations of cycloidal gearboxes.