Sharif Digital Repository

In this paper, the stick-slip motion of a microrobot with two perpendicular vibrational actuators is studied. This motion is based on the friction drive principle. To determine the effective parameters in the motion of microrobot, the equations of motion of the microrobot are derived. To simplify the equations for determining the design parameters, the vibrational actuators are modeled with two perpendicular harmonic forces. To study the motion dynamics of the microrobot, its equation of motion is derived in a nondimensional expression by defining the nondimensional effective parameters. The Fourier expansion (F.E.) method is used to analyze the numerical results and it showed some... 

In this paper, the stick-slip motion of a new type of micro-robot with two perpendicular vibratory actuators is studied which is based on the friction drive principle. The actuators are based on piezo-electric phenomenon which are driven by a harmonic voltage, and both of them are mounted on the micro-robot body. These actuators cause the micro-robot moves forward or backward due to the specified phase difference between the voltages applied to vertical and horizontal actuators. Since the dynamics of the actuators affects on the micro-robot motion, so to derive the equations of motion the coupled dynamics between the body of robot and vibratory masses of actuators are considered, and the... 

The motion of a stick-slip microrobot propelled by its piezoelectric unimorph legs is mathematically modeled. Using a continuously distributed mass model for the robot's body, the working equation of the mechanism is derived based on the assumption of linear Euler-Bernoulli beam theory and linear piezoelectric behavior. Moreover, the required condition for generating net motion is calculated in terms of physical characteristics of the microrobot. It is demonstrated that the higher the friction constant, then a lower average speed is obtained. Also, it is shown that a microrobot with heavier legs can move in a rougher environment. Regardless of the mass proportion between robot's main body... 

In this work, sessile drop and low-bond axisymmetric drop shape analysis methods were coupled to provide some new aspects on stick-slip behavior as well as stick time of a drop on calcite surfaces. Slightly hydrophobic calcite surfaces typified with three irregular roughnesses were used to create irregular surfaces to mimic defects for the water-calcite-air systems. Polishing papers of 200, 600, and 1200 grit and a polishing machine were used to prepare surfaces. X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transform infrared, and atomic force microscopy techniques were employed to evaluate the chemical and physical properties of surfaces. A model was developed to predict...