Phuong Hoai Le

Experiment and simulation of micro-part dynamics with roughness effect

In this study, we perform an experiment and develop a dynamic model that describes the planar motion modes of a micro-part, including two linear motions and one rotational motion, on a saw-tooth surface. In the experiment, the planar motion of the micro-part is obtained by a particle-tracking method. The rotation angle is measured from the principal axis of the micro-part image. In a simulation, contact between the micro-part and the saw-tooth surface is assumed to be the contact between a number of hemispheres on the micropart and the surface, which results in either a point contact or slope contact. The effect of the saw-tooth surface roughness on the contact force at each contact point is modeled as a field of normal vectors. In addition, the roughness of the saw-tooth surface is approximated by superposing white noise on an ideal saw-tooth profile and is used to evaluate the adhesion force. The results show that the model describes the motion modes of a micro-part. Furthermore, the simulated results of the two linear motions are in good agreement with our experimental results from a previous study. The proposed model can be used to improve the design of surfaces for micro-part transport.

A Study on the Motion of Micro-Parts on a Saw-Tooth Surface by the PTV Method

This study investigates the motion of micro parts on several vibratory plates with saw-tooth surface profile driven by a piezoelectric actuator. The surfaces are made of carbide, brass, and zirconia with the same profiles as a saw-tooth. The velocity and position of micro-parts are time-dependently measured by the particle tracking velocimetry (PTV) method where the Canny edge detection technique is used. In the present experiment, 2012-type micro-parts whose dimensions are 2.0 × 1.2 × 0.6 mm3 in length, width, and depth, respectively, are employed. The mass of each micro-part is 7.5 mg. Using a high-speed camera, the tracked longitudinal displacement resolution is found to be about 0.01 mm, which is small in comparison with the length of each micro-part. The obtained results show that unidirectional motion can be attained by the present feeder system. For the same oscillating frequencies and amplitudes applied to the sawtooth surfaces, the motion behavior of micro-parts varies for different experiments and surfaces. This implies that the motion of micro-parts is affected by uncertain causes. However, the probability distribution of the micro-parts’ velocity can be approached by a Gaussian distribution.Copyright

Origami structure toward floating aerial robot

In this paper, we introduce the application of Japanese origami art to the floating system of unmanned helicopter model for the case of emergency landing. The “origami floating system” is integrated compactly in the helicopter and expands by an electronic controlled system when the helicopter lands on water. We tested our proposed floating system using three types helicopters, with the origami made from waterproof paper. The results indicate that the proposed system is feasible for helicopter and other aerial vehicles. In addition, several origami balls were constricted as floating devices for the helicopter. The correlation between the diameter of inflated ball and the size of origami paper sheet, along with the effects of the weight of helicopter on the water, are also investigated in detail.

Feed and align microparts on symmetrically vibrating saw-tooth surface

This paper proposed a model to simulate microparts feeding and an alignment method to conduct microparts following a desired path. On the model aspect, we considered the effect of surrounding fluid the feeding velocity. The attained results show that the model with fluid drag predicted well the behavior and magnitude of the feeding velocity in comparison with experiment data, while the model without fluid drag overestimated the feeding velocity. It implied that fluid plays an important role in the motion of the sub-millimeter microparts. In addition, a simple method to align microparts following a desired path on symmetrical vibrating surface was proposed.

Experiment of Micro-Parts Feeding on Saw-Tooth with the Effect of the Surface Geometry Parameters

In this work, we study experimentally the effect of the geometry parameters of saw-tooth surface and micro-part on the motion of micro-parts. The experiments are performed for a range of saw-tooth pitch, p, micro-part length, l, and exciting frequency applied to the surface, f. By the use of particle tracking velocimetry method, we can achieve time-dependent velocity, and then ensemble-averaged velocity of the micro-parts. The results show that for different l and p but the same relative scale l/p, the profiles of micro-part velocity against the characteristic surface velocity pf are similar. However, they shift along pf axis depending on p. Furthermore, the profiles are the similar for the relative scale l/p of 4 to 100. It seems that the motion of micro-part depends on characteristic surface velocity pf than the relative scale l/p for l/p larger than a certain value.