14th World Congress in Mechanism and Machine Science, Taipei, Taiwan, 25-30 October, 2015

1. Miniature Piezoelectric Mobile Robot driven
by Standing Wave
Hassan Hussein Hariri, Gim Song Soh, Shaohui Foong, Kevin Otto, Kristin Wood
hassan_hariri@sutd.edu.sg
14th World Congress in Mechanism and
Machine Science, Taipei, Taiwan,
25-30 October, 2015

2. Copyright Hassan Hussein Hariri 2015
Overview
 Fundamental Principle of Standing Wave
Ultrasonic Linear Motor
 Robot Structure
 Locomotion principle
 Legs positions for the robot at 𝑓1 & 𝑓3
 Modeling of the piezoelectric unimorph actuator
 Design
 Fabrication
 Experiments
 Conclusion & future work
2

3. Copyright Hassan Hussein Hariri 2015
Fundamental Principle of Standing
Wave Ultrasonic Linear Motor
3
Vibrating beam
Slider
Moving direction

4. Copyright Hassan Hussein Hariri 2015
Fundamental Principle of Standing
Wave Ultrasonic Linear Motor
4
Slider
Moving direction
Vibrating beam

5. Copyright Hassan Hussein Hariri 2015
Robot Structure
 Piezoelectric unimorph actuator with rigidly
attached legs
5
Piezoelectric beam
Elastic beam
Rigid Legs

6. Copyright Hassan Hussein Hariri 2015
Locomotion principle
6
Vibrating beam
Substrate
Vibrating beam
Substrate
Moving direction
Moving direction

7. Copyright Hassan Hussein Hariri 2015
Locomotion principle
7
Vibrating beam
Substrate
Vibrating beam
Substrate
Moving direction
Moving direction
Substrate

8. Copyright Hassan Hussein Hariri 2015
Locomotion principle
8
 Locomotion principle for one leg during one
cycle of motion

9. Copyright Hassan Hussein Hariri 2015
Legs positions for the robot at 𝑓1 & 𝑓3
9

10. Copyright Hassan Hussein Hariri 2015
Modeling of the piezoelectric unimorph
actuator
 Geometric parameters
10
Electric field
𝒙
𝒚
𝒛
𝒍
𝒕 𝒎
𝒕 𝒑
Piezoelectric beam
Elastic beam
Poling
𝒃

11. Copyright Hassan Hussein Hariri 2015
Modeling of the piezoelectric unimorph
actuator
 Kinematics of the deformation
11

12. Copyright Hassan Hussein Hariri 2015
Modeling of the piezoelectric unimorph
actuator
 The dynamic equation of motion
12
(1)
(2)
(3)
(4)
(5)

13. Copyright Hassan Hussein Hariri 2015
Modeling of the piezoelectric unimorph
actuator
 Resonance frequencies and mode shapes (using
eq. 1)
13
(6)
(7)
(8)
(9)
(10)
(11)
(12)

14. Copyright Hassan Hussein Hariri 2015
Design
 NCE53, soft PZT from Noliac Inc.
 Aluminum
 Both the PZT and Aluminum have similar dimensions except for
thickness
14

15. Copyright Hassan Hussein Hariri 2015
Design
 Legs positions for the robot at 𝑓1 = 2.41 kHz &
𝑓3 = 12.77 kHz (using eq. 9 & eq. 10)
15

16. Copyright Hassan Hussein Hariri 2015
Fabrication
 Legs positions on the aluminium beam
16

17. Copyright Hassan Hussein Hariri 2015
Fabrication
 Prototype of the piezoelectric robot with an
embedded mass
17

18. Copyright Hassan Hussein Hariri 2015
Experiments
 𝑓1 = 2.41 kHz (analytically) & 𝑓1 = 2.6 kHz (Experimentally)
18

19. Copyright Hassan Hussein Hariri 2015
Experiments
 𝑓3 = 12.77 kHz (analytically) & 𝑓1 = 12.7 kHz (Experimentally)
19

20. Copyright Hassan Hussein Hariri 2015
Experiments
 Slow motion at 𝑓1 with high speed motion capture system
20

21. Copyright Hassan Hussein Hariri 2015
Experiments
 Speed versus applied voltage on acrylic substrate
21

22. Copyright Hassan Hussein Hariri 2015
Conclusion & future work
 Conclusion
– Inspired from linear ultrasonic motor, the operation
principle for miniature piezoelectric mobile robot is
explained
– A model for unimorph piezoelectric actuator is
developed
– A prototype for the robot is made and experimental
verifications are done
 Future work
– Improve the design to avoid curved motion and keep it
straight in both directions
– Show an onbord electronics for the robot
22

23. QUESTIONS?
23