BUKU ABSTRAK - Universiti Putra Malaysia

Development of a New Minimum Avoidance System for a Behaviour-based Mobile
Robot
Assoc. Prof. Dr. Tang Sai Hong
Omid Motlagh, Napsiah Ismail and Ang Chun Kit
Faculty of Engineering, University Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia.
+603-8946 6332; saihong@eng.upm.edu.my
Keywords: Fuzzy logic, local navigation, minimum avoidance, virtual target, autonomous robotics
Keywords: Antifreeze, protein, peptide, thermal hysteresis
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Science, Technology & Engineering
A new fuzzy logic algorithm is developed for reactive navigation of mobile robots. A pioneer robot perceives
its environment through an array of eight sonar sensors and self positioning-localisation sensors. While the fuzzy
logic body of the algorithm performs the main tasks of obstacle avoidance and target seeking through artificial
potential fields, an actual-virtual target switching strategy resolves the problem of limit cycles in any type of
dead-ends encountered on the way to the target. This is an advantage beyond pure fuzzy logic approaches and
common virtual target techniques. In this work, multiple traps may have any shape or arrangement from barriers
forming simple corners and U-shape dead-ends to loops, maze, snail shape, and other complicated shapes. Robot
trajectories are demonstrated by simulation work and compared with results from other related methods to prove
the robustness of this method.
Novel Antifreeze Peptides derived from Fungal Protein
Dr. Bimo Ario Tejo
Syed Hussinien Hielmie Shah, Mohammad Fairuz Zulkifli, Mohd. Basyaruddin Abdul Rahman, Abdul Munir
Abdul Murad, Nor Muhammad Mahadi, Mahiran Basri, Raja Noor Zaliha Abdul Rahman and Abu Bakar Salleh
Faculty of Science, University Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia.
+603-8946 7488; bimotejo@science.upm.edu.my
Antifreeze proteins play a vital role in the survival of organisms living in sub-zero temperature. The ability
of antifreeze proteins to lower the freezing point without lowering the melting point, called thermal hysteresis, has
attracted increasing interest in the past decade, particularly in the utilisation of antifreeze proteins as cryoprotectant
for biological materials. However, commercial application of antifreeze proteins is hindered by high production
cost due to low yield of protein expression. Short peptide segment derived from functional region of antifreeze
protein that preserves the activity of its parent protein may be seen as potential candidate for a new antifreeze
agent. In this work, we designed antifreeze peptides derived from novel antifreeze protein of Leucosporidium
antarcticum. The design of the peptides is based on the predicted structure of L. antarcticum antifreeze protein,
which has less than 20% homology with other antifreeze proteins in Protein Data Bank. The predicted protein
structure shows four helical segments located in the outer structure of the protein. Our hypothesis is that the L.
antarcticum antifreeze protein utilises these four helical segments to inhibit ice crystal growth by binding to
the ice crystal-liquid water surface. To prove our hypothesis, we designed four peptides derived from helical
segments of L. antarcticum antifreeze protein with various lengths between 25 to 30 residues. Three peptides
possess nonzero thermal hysteresis and result in modification of the ice crystal shape. Two peptides are modified
by Leu/Glu and Gln/Lys replacements in order to create helix-stabilising i, i+4 salt bridges. We found that the
peptides with additional salt bridges have increased thermal hysteresis, which suggests the role of salt bridge in
the stabilisation of antifreeze peptide structure. Our study on molecular dynamics suggests that the increased
activity of modified peptide could be due to the rearrangement of hydrophobic-hydrophilic faces of the peptide.