Centroid

About: Centroid is a research topic. Over the lifetime, 4110 publications have been published within this topic receiving 53637 citations. The topic is also known as: barycenter (geometry) & geometric center of a plane figure.

Collective control of multiple unicycle agents with non-identical constant speeds: Tracking control and performance limitation

Abstract: This paper discusses collective control of multiple unicycle-type vehicles with nonholonomic constraints and non-identical constant speeds, with focus on the design of a tracking controller for a desired target's position and velocity. The tracking control task is divided into several sub-tasks. The group centroid is controlled to track a desired reference velocity, while the reference velocity is constructed with information from the target's position and velocity so that the group centroid can successfully track both the position and velocity of a target vehicle. In order to keep all the agents close to the centroid within a reasonable spacing, an additive spacing controller is devised. We also discuss in detail the performance limitation and trade-offs of the tracking control due to the constraint of non-identical and constant speeds in such a heterogeneous agent group.

A Low-Complexity Multistage Polyphase Filter Bank For Wireless Microphone Detection in CR

Abstract: In this paper, we propose a low-complexity multistage polyphase filter bank for the detection and estimation of center frequency of wireless microphone (WM) in television channels for cognitive radios. The detection precision is directly related to the number of subbands (granularity) in the filter bank. This implies that the computational complexity becomes high if the number of stages and granularity of the filter bank structure are increased. The novelty of the proposed method is the estimation of center frequency with higher precision and reduced computational complexity using the centroid method. The merit of the centroid method is that the presence of WM can be detected along with estimation of center frequency in the first stage, if the WM lies partly in one subband and partly in the adjacent subband. This single-stage detection and estimation of WM significantly reduces computational and hardware complexities as well as latency. However, if the WM appears anywhere exclusively within a single subband, the detection process can be completed in the second stage without ambiguity. A mathematical expression for calculating the center frequency of WM from the subband energy (power) using centroid method is also derived and presented. The proposed scheme is analyzed and validated through extensive simulations for the detection of WM. The error in estimation of center frequency in most of the cases is less than 4 % for SNR variations from 0 to ź20 dB.

Optimal Principle of Bone Structure

Abstract: Bone modeling and remodeling is an optimization process where no agreement has been reached regarding a unified theory or model. We measured 384 pieces of bone in vivo by 64-slice CT and discovered that the bone's center of mass approximately superposes its centroid of shape. This phenomenon indicates that the optimization process of non-homogeneous materials such as bone follows the same law of superposition of center of mass and centroid of shape as that of homogeneous materials. Based upon this principle, an index revealing the relationship between the center of mass and centroid of shape of the compact bone is proposed. Another index revealing the relationship between tissue density and distribution radius is followed. Applying these indexes to evaluate the strength of bone, we have some new findings.