1 Challenge the future 1 1 Structural control method research for MAV application Yao Lu Chairman : Prof. Dr. Fred van Keulen Supervisor: Dr. Hans Goosen, Hugo Peters

2 Challenge the future 2 2 Content Introductions Introduction to the concept of MAV Introduction to the task Structural control methods and actuator screening Tests Conclusion and recommendation

3 Challenge the future 3 3 Introduction to Micro Air Vehicle(MAV)

4 Challenge the future 4 4 Introduction to the task The aim of this thesis is to investigate approaches to modify the structure stiffness

5 Challenge the future 5 5 Requirement approximation The stiffness change requirement is done and it is supposed that the one that can serve more than 1% of stiffness modification is satisfied

6 Challenge the future 6 6 Introduction to the task It is hardly possible to investigate the problem on the vehicle currently The research is based on a simplified model

7 Challenge the future 7 7 Content Introductions Structural control methods and actuator screening Tests Conclusion and recommendation

8 Challenge the future 8 8 Collection of stiffness change methods Various methods can be used for the beam stiffness change Before screening of these methods, actuators should be screened

9 Challenge the future 9 9 Actuator screening Actuators can be grouped into four groups according to different mechanisms Actuation Electric field Electro- Magnetic Electro- Magnetic Temperature Magnetic field

10 Challenge the future 10 Challenge the future 10 Challenge the future Actuator screening The generation of magnetic field requires too much additional weight

11 Challenge the future 11 Challenge the future 11 Challenge the future Actuator screening Two groups of actuators are not favored in MAV application for the generation of magnetic field requires too much weight Actuation Electric field Electro- Magnetic Electro- Magnetic Temperature Magnetic field

12 Challenge the future 12 Challenge the future 12 Challenge the future Criteria of methods screening Piezoelectric material and Shape-memory-alloy material are representatives of the remained two groups of active materials The stiffness change, the energy cost and the control time should be analyzed for each method. Piezo Piezo passive or SMA-two-state

13 Challenge the future 13 Challenge the future 13 Challenge the future Piezo passive stiffness method The piezo passive stiffness method uses the mechanism that the stiffness of a short circuited piezo is lower than that in open circuit condition The stiffness change is obtained by switching between two electrical conditions of electrodes.

14 Challenge the future 14 Challenge the future 14 Challenge the future SMA-two-state method mechanism The Youngs modulus of SMA material depends on temperature

15 Challenge the future 15 Challenge the future 15 Challenge the future Screening of the methods After screening using theoretical work and simulations, the piezo passive method is selected. MethodsStiffness change Energy costControl time Schematic figure Stressing method Sandwich method Curving method SMA-two- state method 1W0.1s Piezo passive stiffness 0W0s

16 Challenge the future 16 Challenge the future 16 Challenge the future For a simplified model, the stiffness change depends on the Youngs modulus ratio and thickness ratio between beam material and piezo material Piezo passive stiffness method

17 Challenge the future 17 Challenge the future 17 Challenge the future The stiffness change is about 20% Piezo passive stiffness method

18 Challenge the future 18 Challenge the future 18 Challenge the future Piezo passive stiffness method However, there are effects that will reduce the effectiveness of this method such as the effect of glue.

19 Challenge the future 19 Challenge the future 19 Challenge the future Piezo passive stiffness method The effect of this method is greatly reduced, from about 20% to about 4%. Experiments should be done to verify the effectiveness of this method in practice.

20 Challenge the future 20 Challenge the future 20 Challenge the future Content Introductions Structural control methods and actuator screening Tests Conclusion and recommendation

21 Challenge the future 21 Challenge the future 21 Challenge the future Experiment set-up Static test is performed

22 Challenge the future 22 Challenge the future 22 Challenge the future Experiment result Deformation for open circuit (um) Deformation for short circuit (um) Stiffness change 1.44%

23 Challenge the future 23 Challenge the future 23 Challenge the future Experiment result Limited by piezo patch numbers, limited tests are done Tested stiffness change is less than expected Sample No. MaterialThickness (mm) Stiffness change from test Stiffness change from simulation 1,2,3Aluminum0.5,0.8,1.0 4Brass %4.38% 5Steel1.00.4%4.2%

24 Challenge the future 24 Challenge the future 24 Challenge the future Content Introductions Structural control methods and actuator screening Tests Conclusion and recommendation

25 Challenge the future 25 Challenge the future 25 Challenge the future Conclusion and recommendation It shows that the passive stiffness method can induce more than one percent of stiffness change for certain material. For the future research, it is better to use material and manufacturing with more precision. The integration of piezo ceramic material to the structural material without glue can be researched. Future colleagues may work in the direction to enhance the effectiveness of the passive stiffness method by electronics.

26 Challenge the future 26 Challenge the future 26 Challenge the future Nature is a good teacher to human beings ---Laozi ( BC)