Jun-ho Park

An efficient path planning method for a cleaning robot based on ceiling vision

We propose an efficient path planning method based on an algorithm that aligns the geometric pattern of a ceiling with the heading angle of a cleaning robot. This algorithm results in a 22% faster cleaning time for a well-aligned cleaning path. We implemented and verified our proposed method for a cleaning robot using a ceiling vision simultaneous localization and mapping (SLAM) algorithm.

Optimal patterns for sequentially multiple focusing in high intensity focused ultrasound and their application to thermal dose

The purpose of this study is to propose a new method for multiple-focus generation to shorten overall treatment time as well as to avoid the formation of high intensity regions outside the target volume. A numerical simulation of the acoustic fields produced by a 1017-element spherical-section ultrasound phased array transducer operating at a frequency of 1.0MHz with 16 cm radius of curvature is performed for the proposed multiple-focus generation. The total foci are partitioned into the several patterns because multiple focusing generally gives rise to the grating lobes outside of the three dimensional region of interest even if applying the optimization of intensity gain in determining the phases and amplitudes of the excitation source vector. The optimization problem is repeatedly formulated in term of the focal points until the multiple-focus patterns cover all the focal points. Genetic algorithm is used for selecting the patterns without the grating lobes. The obtained set of multiple-focus patterns ...

Multiple focus beamforming of phased array to suppress grating lobes for HIFU

To reduce the treatment time for HIFU(High Intensity Focused Ultrasound), increasing the ablation volume by generating multiple foci can be a promising scheme. It is reported that as the number of foci increases, grating lobes are generated more. Here, we present a method to suppress grating lobes while generating a multiple focus field by setting the pressure of grating lobe regions to be zero. Among all solutions to generate desired multiple foci, one solution is found by imposing a constraint of grating lobe suppression. It is an extension of the minimum norm solution of the conventional multiple focus method. This method can be also used to protect some important tissue areas from collateral heat damage.