Many industrial robotic arms are used for general pick and place operations. These particular robotic arms are usually driven by timing belts, which limit the speed of the pick and place operation due to undesirable vibration at the end of the motion. This undesirable vibration is attributed to the timing belt’s flexibility, which introduces resonance inside the servo bandwidth. The objective of this paper is to demonstrate a simple and robust approach, which can be easily implemented in real time, to control robot belt flexibility. By using standard industrial accelerometers and a sliding observer, all the information required to implement a control can be estimated. A description of the sliding observer design and the vibration suppression controller are presented in this paper. Simulation results show how this technique can successfully reduce the robot end-point vibration and improve the bandwidth of the servo controller.

Volume Subject Area:
Dynamic Systems and Technology
Keywords:
Robotics, flexible joints, sliding observers, acceleration feedback
Topics:
Feedback, Robotics, Robots, Vibration, Control equipment, Servomechanisms, Accelerometers, Belts, Design, Resonance, Simulation results, Timing belts, Vibration suppression
1.
Walcott
B. L.
,
Corles
M. J.
, and
Zak
S. H.
, “
Comparative study of non-linear state-observation techniques
,”
International Journal of Control
, Vol.
45
, pp.
2109
–
2132
,
1987
.
2.
Misawa
E. A.
and
Hedrick
J. K.
, “
Nonlinear observers- A state-of-the-art survey
,”
ASME J. of Dynamic Systems, Measurement and Control
, Vol.
111
, pp.
344
–
352
,
1989
.
3.
Thein, M.-W. and Misawa, E.A., “Comparison of the sliding observer to several state estimators using a rotational inverted pendulum,” in: Proc. of the 34th IEEE Conf. on Decision and Control, New Orleans, LA, pp. 3385–3390, 1995.
4.
Azemi, A. and Yaz, E.E., “Comparative study of several nonlinear stochastic estimators,” in: Proc. of the 38th Conf. on Decision & Control, Phoenix, Arizona, pp. 4549–4554, 1999.
5.
Bona, B. and Indri, M., “Analysis and implementation of observers for robotic manipulators,” Proc. of the IEEE conf. on Robotic and Automation, pp. 3006–3011, 1998.
6.
Gelb, A., Applied Optimal Estimation, MIT Press, Cambridge, MA, 1974.
7.
Gauthier
J. P.
,
Hammouri
H.
, and
Othman
S.
, “
A simple observer for nonlinear systems: Applications to bioreactors
,”
IEEE Transactions on Automatic Control
, Vol.
37
, pp.
875
–
880
,
1992
.
8.
Krener
A. J.
and
Isidori
A.
, “
Linearization by output injection and nonlinear observers
,”
Systems Control Letters
Vol.
3
, pp.
47
–
52
,
1983
.
9.
Keller
H.
, “
Non-linear observer design by transformation into a generalized observer canonical form
,”
International Journal of Control
, Vol.
46
, pp.
1915
–
1930
,
1987
.
10.
Drakunov, S.V., “Sliding mode observers based on equivalent control method,” Proc. of the 31st IEEE Conf. on Decision and Control, Tucson, Arizona, pp. 2368–2369, 1992.
11.
Slotine
J.-J. E.
,
Hedrick
J. K.
and
Misawa
E. A.
 “
On sliding observers for nonlinear systems
,”
ASME J. of Dynamic Systems Measurement and Control
, Vol.
109
, pp.
245
–
252
,
1987
.
12.
Nicosia
S
,
Tornei
P.
, and
Tornambe´
A.
, “
An approximate observer for a class of nonlinear systems
,”
Systems and Control Letters
, Vol.
12
, pp.
43
–
51
,
1989
.
13.
Zaki A., Elbeheiry, E., ElMaraghy, W., “Variable Structure Observer Design for Flexible-Link Manipulator Control,” Trans. of the Canadian Society of Mechanical Engineers, Vol. 27, No. 2, 2003.
14.
Massoud
A. T.
,
ElMaraghy
H. A.
, and
Lahdiri
T.
, “
On the robust nonlinear motion position and force control of flexible joints robot manipulators
,”
Journal of Intelligent and Robotic Systems
, Vol.
25
, pp.
227
–
254
,
1999
.
15.
The Mathworks, Inc., “MATLAB/Simulink version 6.5 Release 13,” Natick, MA 01760, USA, 2002.
16.
Stoten, D. P., Model Reference Adaptive Control of Manipulators, Research Studies Press Ltd., Somerset, United Kingdom, 1990.
This content is only available via PDF.
Copyright © 2005
 by ASME
You do not currently have access to this content.