![](bg4.png)
Using heat in order to activate SMA wire, a
human operator will increase or decrease the amount
of heat in order to assure a desired position to
robotic link. Because of medium temperature
influence, can not be establish, apriori, a clear
control law, available for all the points of the robotic
structure workspace. A simple and efficent control
structure can be implemented.
Figure 9: Fuzzy control structure.
For an efficient control it is proposed the
following definition for input and output members:
- input 1 is the first derivate of pozition error, with 3
fuzzy member: Negative, Zero, Pozitive
- input 2 is pozition error with 3 fuzzy member:
Negative, Zero and Pozitive
- output is temperature heating with 3 fuzzy
member: Temperature Negative (temperature under
austenitic start transformation), Temperature Zero
(temperatures between start and final austenitic
transformation), Temperature Positive (temperature
above temperature of final austenitic
transformation).
Table 1: Fuzzy rules for the proposed controller.
e
&
e
P Z N
P TP TP TP
Z TZ TZ TZ
N TN TN TN
The result of the numerical simulation are
promising, related to the simplicity of the control
structure, for the case of the sinusoidal reference
with frecvency of 5 rad/sec.
Figure 10: Fuzzy robotic structure output evolution.
5 CONCLUSIONS
The simulations, the mathematical model and the
initial experiments developed in the article offer a
background in studying the serial link robotic
control possibilities. The results respect the real
evolution of the structure. In the future, the authors
will explore improvement of the control
performnces and the extension of the experiments to
n link robotic structure.
REFERENCES
Cheng, F. T., "Control and Simulation for a Closed
Chain Dual Redundant Manipulator System",
Journal of Robotic Systems, pp. 119 - 133, 1995
Cheng, F. T., Orin,D. E., "Optimal Force Distribution
in Multiple-Chain Robotic Systems", IEEE Trans. on
Sys. Man and Cyb.", Jan., 1991, vol. 21, pp. 13 – 24
Cheng, F. T., Orin,D. E., , "Efficient Formulation of
the Force Distribution Equations for Simple Closed -
Chain Robotic Mechanisms", IEEE Trans on Sys.
Man and Cyb.,Jan. 1991, vol. 21, pp. 25 -32.
Delay, L., Chandrasekaran M., 1987. Les Editions
Physique. Les Ulis.
Faravelli L and Marioni A, 1996, Exploiting SMA Bars in
Energy Dissipators, Proceedings of the 2nd
International Workshop on Structural Control, Hong
Kong HKUST 41-50
Funakubo H., 1987, Shape Memory Alloys, Gordon and
Breach Science Publishers
Ivanescu, M., Dynamic Control for a Tentacle
Manipulator, Proc. of Int. Conf., Charlotte, USA,
1984
Ivanescu, M.,Stoian,V., A Variable Structure Controller
for a Tentacle Manipulator, Proc. of the 1995 IEEE
Int.Conf. on Robotics and Aut., Nagoya, Japan, May
21 - 27,1995, vol. 3, pp. 3155 - 3160
Lotfi A. Zadeh , Fuzzy sets, Information and Control 8,
338-353, 1965.
Mason, M. T., "Compliance and Force Control",
IEEE Trans. Sys. Man Cyb., Nr. 6, 1981, pp. 418 –
432
Ross, T.J., Fuzzy Logic with Engineering Applications,
Mc.Grow Hill , Inc., 1995
Soo Yeong Yi, A robust Fuzzy Logic Controller for Robot
Manipulators, IEEE Trans. on Systems, Man and
Cybernetics, vol 27, No 4, 706-713, 1997
Tao, C.W. ,Design of Fuzzy-Learning Fuzzy Controllers ,
FUZZ IEEE'98, 416-421
Utkin, V. I., Variable structure systems with sliding
modes, IEEE Trans. Automat. Contr., vol. AC-22, pp.
212-222, 1977.
Utkin, V. I., Variable structure systems and sliding
mode\—State of the art assessment, Variable Structure
Control for Robotics and Aerospace Applications, K.
D. Young, Ed. , New York: Elsevier, pp. 9-32, 1993.
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