1. University of Minnesota
A New Design of Mastication Machine using Linear Motors
Lianshan Lin, Alex Fok, Ralph Delong, Maria Pintado, William H. Douglas
Minnesota Dental Research Center for Biomaterials and Biomechanics
University of Minnesota

2. Simulate the real chewing action Long lasting working life
Targets:
Simulate the real chewing action
Long lasting working life
Robust and stable
Energy efficient and lower cost

3. Adjustable wear frequency
Previous designs – ACTA wear machine
Apply load by spring
Adjustable wear frequency
Two-body or three-body wear
Specimen worn by steel wheel
Multi specimens in one test
Academic Centre for Dentistry Amsterdam (ACTA), 1994

4. Albert-Ludwigs University and Christian-Albrechts University, 1999
Previous designs – 2-axis chewing simulator
Albert-Ludwigs University and Christian-Albrechts University, 1999

5. Bialystok Technical University, 2006
Previous designs – tribometer
Bialystok Technical University, 2006

6. Waseda University, WOJ-1 RII, 2002
Previous designs – mastication robot
Waseda University, WOJ-1 RII, 2002

7. jaw motion simulator 6 linear actuators, 3 DOFs
Previous designs – robotic jaw
jaw motion simulator
6 linear actuators, 3 DOFs
Massey University, 2002

8. force sensor underneath the second molars
Previous designs – Dento-Munch
Hexapod robot, 6 DOFs
6 actuators
force sensor underneath the second molars
University of Bristol, 2009

9. University of Minnesota, MDRCBB, 1984
Previous designs – ART-I and ART-II
ART - II
ART - I
University of Minnesota, MDRCBB, 1984

10. When following the FDA guidelines on good laboratory practice (GLP),
Comparison
When following the FDA guidelines on good laboratory practice (GLP),
ONLY the expensive MTS wear simulator is a qualified machine to test wear in vitro;
ONLY with the MTS method have wear parameters and influencing factors been documented and verified.
----S.D. Heintze, How to qualify and validate wear simulation devices and methods, dental materials 2 2 ( ) 712–734

11. Chewing forces recorded by EMG sensor [1]
Design objective – chewing forces
Chewing forces recorded by EMG sensor [1]
Representation of masticatory force profile by a sine function [2]
[1] R. González, I. Montoya, J. Cárcel, Review: the Use of Electromyography on Food Texture Assessment, Food Science and Technology International, Dec 2001 vol. 7 no
[2] J. Ahlgren and B. Owall, “Muscular activity and chewing force: A polygraphic study of human mandibular movements,” Arch. Oral Biol., vol. 15, pp , Apr

12. Machine setup

13. Hydraulic motor controller
Design
Hydraulic motor controller
Vertical motion
Load cell
Horizontal motion
Linear motor controller
Connection Overview

14. Hardware connection Signal recording Load cell Vertical stroke LVDT PC
Analog sine wave
Digital stop trigger PC
User Interface
Data Storing
Command
MTS controller
Motion of hydraulic actuator
Load cell
Vertical stroke LVDT
Linear motor controller
Synchronized horizontal motion
Stroke sensor
Signal recording

15. Control signals
Vertical
load control
Horizontal
displacement control

16. Resin disk, at the bottom
Wearing test samples
Cusp tip, on the top
Resin disk, at the bottom

17. Profiling results

18. Disc volume change (mm3)
Wearing results
Disc volume change (mm3)
Cusp tip
Volume change (mm3)
Maximum depth
(μm)
Mean depth (μm)
Area (mm2)
ART-1
Coated disc
0.004±0.001
18.731±2.384
6.699±4.421
0.625
Uncoated disc
0.006±0.001
26.605±2.298
10.561±6.647
0.540
ART-3
18.166±2.739
8.653±4.895
0.440
32.535±2.025
12.599±11.107
0.460

19. Working Noise (db, background 35db)
Comparisons of other working parameters
Power (W)
Size (m3)
Working Noise (db, background 35db)
Hydraulic Pump
Controller
ART-1
5060
N/A
2.88 72
ART-3
MTS Mini Bionix II
460
2.376 42
Baldor Linear Motor
617 37

20. Conclusions: Future work:
The new design of ART-III machine is equivalent to previous machines in results of chewing tests.
The system of ART-III is robust and stable in testing.
The using of linear motor makes the system more efficient in power consumption, smaller in size and less noisy.
Future work:
Design a new machine using linear motors only to replace current hydraulic systems.