In-flight control of MAV wing camber using Shape Memory Alloy Actuators and flex sensor

Kamalakannan, GM and Navaneetha, S (2014) In-flight control of MAV wing camber using Shape Memory Alloy Actuators and flex sensor. In: National Symposium on Instrumentation (NSI-39), 15 Oct 2014, Gurukul Kangri University Haridwar.

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    Abstract

    Objective/Aim: A morphing system that can dynamically change the camber or shape of Micro Air Vehicle wing provides specific aerodynamic benefits by increasing the lift coefficient. Though many research papers have reported the benefits of morphing, there are hardly any reports on morphing of MAV during flight. The challenge is to measure, effect and control the deflection angle of the wing within the constraints of space (few square centimeter), power (< 5W) and weight (< 8g) in MAV. This paper presents a flex sensor and Shape Memory Alloy (SMA) based in-flight wing deflection measurement and control system. A novel method of transmission of deflection angle and SMA parameters along with other flight data to the Ground Control Station (GCS) and their transfer to MATLAB for online analysis is also presented. Methods and materials: Fixed wing MAV, namely 'black kite' was chosen for the morphing trials. Morphing involved change of camber through drooping of wing Leading Edges (LE) along the plane's lateral axis. A flex sensor bonded to the wing, changes its resistance as a function of wing deflection. This was read as a voltage signal in the Ardu-ino flight controller. To overcome the inaccuracy of flex sensor, software-based auto nulling and averaging were implemented as a sub-function of auto pilot code. The actuator requirements for morphing were experimentally determined and a NiTinol SMA wire of appropriate dimension was chosen. SMA actuator generates force and displacement due to temperature induced phase transformation, which can be controlled by varying the magnitude and duration of SMA current. This was realized by Pulse Width Modulation of SMA current through a MOSFET. A PID algorithm with integral reset implemented on the Ardu-ino controller, computes the required pulse width based on the error between actual and set deflection angles (commanded by the ground pilot or the auto pilot). Using a Zigbee transceiver pair and by modifying the auto pilot and GCS codes (open source) the deflection angle and SMA parameters were transmitted, extracted and fed to MATLAB for online trending and other analysis.

    Item Type: Conference or Workshop Item (Paper)
    Subjects: AERONAUTICS > Avionics & Aircraft Instrumentation
    Division/Department: CSMST, CSMST
    Depositing User: Mrs Manoranjitha M D
    Date Deposited: 27 May 2016 15:03
    Last Modified: 27 May 2016 15:03
    URI: http://nal-ir.nal.res.in/id/eprint/12479

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