The modulation and control of gecko＇s foot movements were studied electrophysiologically in order to design the motor control system of a gecko-mimic robot. In this study （1） the anatomy of the peripheral nerves controlling the gecko＇s foot movements was determined; （2） the relationship between the limb nerves of the gecko and its foot motor patterns was studied; （3） the afferent impulses of the nerves evoked by rubbing the gecko＇s toes and palm were recorded; （4） copying the natural patterns of movement of the gecko＇s foot （abduction, adduction, flexion, and revolution） and its limb nerve modulation and control mechanism, the nerves were stimulated under computer control, and the results recorded by CCD. Results suggest that gecko＇s foot movements can be successfully controlled by artificial electrical signals.
Ion-exchange Polymer Metal Composites （IPMC） are a new class of intelligent material that can be used effectively as actuators and artificial muscles. IPMC was fabricated and its displacement and force characteristics were investigated with respect to voltage, frequency and waveform of the controlling signal. A square waveform input generated slightly larger displacement and force than sinusoidal or triangular waveform. When the voltage was increased and the frequency was decreased, displacement and force were both increased. However, although the bending deformation of IPMC was large, the output force was much lower than we expected. Improvement of the force output is key and is the main obstacle to be overcome in order to make IPMC of practical use.
Geometric and micro-structure design, tribology properties of beetle joints were experimentally studied, which aimed to enlighten ideas for the joint design of MEMS.The observation by using SEM and microscopy suggested that beetle's joints consist of a concave surface matched with a convex surface. The heads of the beetles, rubbing with flat glass, were tested in fresh and dried statuses and compared with sapphire ball with flat glass. Frictional coefficient of the joint material on glass was significantly lower than that of the sapphire sphere on glass. The material of the joint cuticle for convex surface is rather stiff (the elastic modulus 4.5 Gpa) and smooth. The surface is hydrophobic (the contact angle of distilled water was 88.3° ). It is suggested here that the high stiffness of the joint material and hydrophobicity of the joint surface are parts of the mechanism minimizing friction in insect joints.
