Robust adaptive sliding mode admittance control of exoskeleton rehabilitation robots

Document Type : Article

Authors

1 School of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, P.O. Box 11155-9567, Tehran, Iran

2 Department of Mechanical Engineering, Shiraz University, Shiraz 71936, Iran

Abstract

A nonlinear robust adaptive sliding mode admittance controller is proposed for exoskeleton rehabilitation robots. The proposed controller has robustness against uncertainties of dynamic parameters using an adaptation law. Furthermore, an adaptive Sliding Mode Control (SMC) scheme is employed in the control law to provide robustness against disturbances (non-parametric uncertainties) with unknown bounds. For this purpose, another adaptation law is defined for the variation of the SMC gain. The proposed scheme is augmented with an admittance control method to provide compliance for the patient during interaction with the rehabilitation robot. The stability of the proposed controller and the tracking performance of the system are proven using the Lyapunov stability theorem. To verify the effectiveness of the proposed control method, some simulations are conducted for a nonlinear lower-limb exoskeleton robot interacting with a patient leg via some braces. Based on the obtained results, the controller is able to provide a flexibility for the patient and appropriately respond to his/her non-compliant interaction torques. Moreover, the proposed controller significantly reduces the chattering of the input torques in comparison with a previous adaptive control method with a constant SMC gain, while it maintains a similar tracking performance. 

Keywords

Main Subjects


References
1. Abbot, J., Nagy, Z., Beyeler F., and Nelson, B.
\Robotics in the small", IEEE Robotics & Automation
Magazine, 14(2), pp. 92-103 (June, 2007).
2. Feng, J. and Kwon Cho, S. \Mini and micro propulsion
for medical swimmers", Micro Machines, 5, pp. 97-113
(2014).
3. Edd, J., Payen, S., Rubinsky, B., Stoller, M.L., and
Sitti, M. \Biomimetic propulsion for a swimming
surgical micro-robot", IEEE/RSJ Intelligent Robotics,
3, pp. 2583-2588 (2003).
4. Purcell, E.M. \Life at low Reynolds number", American
J. Physics, 45(1), pp. 3-11 (1977).
5. Purcell, E.M. \The eciency of propulsion by a rotating

agellum", The National Academy of Sciences of
the USA (PNAS), 94(21), pp. 11307-11311 (1997).
6. Darnton, N.C., Turner, L., Rojevsky, S., and Berg,
H.C. \On torque and tumbling in swimming Escherichia
coli", Journal of Bacteriology, 189(5), pp.
1756-1764 (2007).
7. Chattopadhyay, S., Moldovan, R., Yeung, C., and Wu,
X.L. \Swimming eciency of bacterium Escherichia
coli", PNAS, 103(37), pp. 13712-13717 (2006).
8. Behkam, B. and Sitti, M. \Design methodology for
biomimetic propulsion of miniature swimming robot",
Trans. ASME J. Dyn. Sys. Meas. Control, 128, pp.
36-43 (2006).
9. Xu, T., Hwang, G., Andre , N., and Regnier, S.
\In
uence of geometry on swimming performance of
helical swimmers using DoE", Springer, Journal of
Micro-bio Robotics, 11(1-4), pp. 57-66 (2015).
10. Temel, F. and Yesilyurt, S. \Characterization and
modeling of micro swimmers with helical tails and
cylindrical heads inside circular channels", ASME
Conference, 16-19 June (2013).
11. Gray, J. and Hancock, G.J. \The propulsion of seaurchin
spermatozoa", J. Exp. Biol., 32, pp. 802-814
(1955).
12. Lighthill, J. \Flagellar hydrodynamics: the John von
Neumann lecture", SIAM Rev., 18(2), pp. 161-230
(1976).
13. Taylor, G.I. \Analysis of the swimming of microscopic
organisms", P. Roy. Soc. Lond. A Mat., 209(1099),
pp. 447-461 (1951).
14. Batchelor, G.K. \Slender-body theory for particles of
arbitrary cross-section in Stokes
ow", Journal of Fluid
Mechanics, 44(03), p. 419 (1970).
15. Brennen, C. and Winet, H. \Fluid mechanics of
propulsion by cilia and
agella", Annul. Rev. Fluid
Mech., 9, pp. 339-398 (1977).
16. Garica, J., Torre, D.L., and Bloom eld, V.A. \Hydrodynamic
theory of swimming of
agellated microorganism",
Biophysical Journal, 20, pp. 49-67 (1977).
17. Johnson, R. and Brokaw, C. \Flagellar hydrodynamics:
A comparison between resistive-force theory and
slender-body theory", Biophysical Journal, 25(1), pp.
113-127 (1979).
18. Fei, Y., Yu, H., and Burrows, B. \A review of methods
for hydrodynamic analysis of helical swimming
agella",
18th International Conference on Automation
and Computing (ICAC), pp. 1-8 (2012).
19. McCarter, L., Hilmen, M., and Silverman, M. \Flagellar
dynamometer controls swarmer cell di erentiation
of V. parahaemolyticus", Cell, 54, pp. 345-351 (1988).
20. Reynolds, O. \An experimental investigation of the
circumstances which determine whether the motion
of water shall be direct or sinuous and of the law of
resistance in parallel channels", Philosoph. Trans. R.
Soc. Lond., 174, pp. 935-982 (1883).
21. Terashima, H., Kojima, S., and Homma, M. \Flagellar
motility in bacteria structure and function of
agellar
motor", International Review of Cell and Molecular
Biology, 270, pp. 39-85 (2008).
22. Shi, L., Guo, S., and Asaka, K. \A novel jelly sh-like
biomimetic microrobot", IEEEI/ICME International
Conference on Complex Medical Engineering, pp. 277-
281 (2010).
23. Jayender, J., Patel, R.V., and Nikumb, S. \Robotassisted
Active catheter insertion: Algorithms and
experiments", The International Journal of Robotics
Research, 28(9), pp. 1101-1117 (2009).
24. Kim, B., Lee, S., Park, J.H., and Park, J.O. \Design
and fabrication of a locomotive mechanism for
capsule-type endoscopes using shape memory alloys",
IEEE/ASME Transactions on Mechatronics, 10, pp.
77-86 (2005).
H. Sayyaadi and Sh. Bahmanyar/Scientia Iranica, Transactions B: Mechanical Engineering 25 (2018) 2616{2627 2627
25. Langbein, S. and Czechowicz, A. \Adaptive resetting
of SMA actuators", Journal of Intelligent Material
Systems and Structures, 23(2), pp. 127-134 (2012).
26. Kim, B., Lee, M.G., Lee, Y.P., Kim, Y., and Lee, G.
\An earth worm like micro robot using shape memory
alloy actuator", Sensors and Actuators A: Physical,
125(2), pp. 429-437 (2006).
27. Apalkov, A., Fernandez, R., Fontaine, J.G., Akin-
ev, T., and Armad, M. \Mechanical actuator for
biomimetic propulsion and the e ect of the caudal n
elasticity on the swimming performance", Sensors and
Actuators A: Physical, 178, pp. 164-174 (2012).
28. Wang, Zh., Hang, G., Li, J., Wang, Y., and Xiao, K.
\A micro-robot sh with embedded SMA wire actuated

exible biomimetic n", Sensors and Actuators
A: Physical, 144(2), pp. 354-360 (2008).
29. Georges, T., Brailovski, V., and Terriault, P. \Characterization
and design of antagonistic shape memory alloy
actuators", Smart Materials and Structures, 21(3),
8 pages (2012).
30. Rao, A. and Reddy, J.N. \Design of shape memory
alloy (SMA) actuator", Computational Mechanics,
Springer, ISBN 978-3-319-03188-0 (2015).
31. Lauga, E. \Bacterial hydrodynamics", Annu. Rev.
Fluid Mech., 48, pp. 105-130 (2016).
32. Chwang, T. and Wu, T. \A note on the helical
movement of microorganisms", Proceedings of Royal
Society of London, B, 178, pp. 327-346 (1971).