Reliable and lightweight primary flight control actuation using magneto-rheological clutches in slippage

Abstract

Replacing aircraft hydraulic actuators with ElectroMechanical Actuators (EMAs) is seen as a necessary step towards the development of safer and more efficient aircraft with minimal environmental impact. EMAs are commonly used in a wide range of applications as they have improved efficiency over hydraulic actuators. However, in their current form, EMAs do not comply with the stringent weight and reliability requirements of primary flight control applications. This paper describes an Active Torque Distribution (ATD) system that could meet flight control reliability requirements, be lightweight, and increase the dynamic performance of current flight controls. The proposed ATD system uses magneto-rheological clutches to modulate the torque transferred from a centralized velocity source to various control surfaces. The fundamental advantage of this approach is found in the fluidic nature of magneto-rheological clutch interfaces which transmit torque without any solid mechanical contact thus preventing wear and failure causing mechanical seizure. The analytical study used to scale an ATD system and an analogue EMA system based on a representative flight control application shows that the proposed ATD system is 42% lighter than a system composed of EMAs and has a weight similar to that of current hydraulic actuators. Furthermore, this study demonstrates that ATD systems add ~100x less inertia to flight surfaces than EMAs allowing implementation of load alleviation control algorithms requiring high frequency motion (~30 Hz). A proof-of-concept clutch and controller confirm the analytical predictions and validate the possibility of using magneto-rheological clutches for flight control actuation.

Performance Study of Low Inertia Magnetorheological Actuators for Kinesthetic Haptic Devices

“…Other simulation parameters include a 1 ms pure delay for MR actuators, corroborating experiments and previous results for similar designs [15]. Discretization and sampling time of all systems are considered infinite for simplicity.…”

On the relation between the Mason number and the durability of MR fluids

“…This architecture is particularly well suited for human-robot interaction due to its inherent safety (low inertia) and transparency (high bandwidth and back-drivability) [8]. The absence of catastrophic failure scenarios for the CSA configuration is also of great interest for applications requiring high reliability such primary aircraft flight controls [9].…”

“…This results in a lightweight system since the power source can be sized for the peak power of the whole system instead of each individual output. In one study, a weight reduction of about 40% was found when compared to an equivalent electro-mechanical actuator (EMA) system [9]. Furthermore, the clutches isolate the output from the input power source, resulting in an output inertia over 100 times smaller than an equivalent EMA system.…”

“…The clutches also nullify nonlinear effects, such as gear backlash, present in EMA systems, resulting in high controllability and bandwidth. Reliability and jam-free operation is achieved using redundant clutches and transmissions, allowing critical aeronautical applications, such as aircraft primary controls, to adopt this architecture [9]. These advantages over EMA's make the CSA configuration very attractive for robotic applications as well as robot-human interactions [3].…”

A magnetic screw pump for magnetorheological clutch durability enhancement

“…During operation, the torque transmitted to the output of each clutch is controlled by the modulation of the magnetic field intensity. The fast dynamics of MR clutches (Viau et al, 2017) coupled with their fundamental robustness and reliability due to the absence of metal–metal contacts make MR actuators of interest to the aerospace industry, for applications such as aircraft primary flight control (Chouinard et al, 2015). However, given the dissipative nature of MR clutches, magnetorheological fluid (MRF) durability represents an important challenge.…”